The family's coming, the family's coming - to arms, to arms!

With a station wagon full of gifts, food and clothes - or at National Airport lugging a station-wagonful of the same stuff - here they are for Christmas, and it's up to you to entertain them for as long as their patience holds out.

Okay, trim the tree; roast chestnuts; talk about home. That leaves you with a week or so of mostly nothing. What to do with three to 30 people in the nation's capital at Christmas?

Plenty.

So much, in fact, you'd better start planning the weeks before and after Christmas right now - by the Monday before Christmas, the well-prepared Washington host should know this by heart.

Seven special performances comprise the Kennedy Center's Holiday Festival Dec. 23-31, for which you can buy tickets starting Dec. 11. Regularly scheduled holiday concerts and two plays ("First Monday in October" with Henry Fonda and Jane Alexander and "Paul Robeson" with James Earl Jones) are also running at the Kennedy Center in the weeks before and after Christmas, and you'd better buy those tickets soon.

Furthermore: Special events at the Smithsonian's museums span the same two weeks and include a film festival, craft demonstrations, caroling, puppet shows and a Christmas tree exhibit. "Two Gentlemen of Verona" are visiting the Folger. A "Disco Santa" and a traveling puppet-marionette show are visiting the city's recreation centers, and a children's musical called "Santa and the Haunted House" will be playing at Howard University's Ira Aldridge Theater. And those are just the continuing events, let alone the one-shots.

TO make planning easier, here is a homogenized list of the continuing, the one-night-only and the anytime events. Save it. Tape it on the refrigerator. Consult it when cabin fever sets in. But especially, use it now - while there's time. MONDAY, DECEMBER 19

The folks want to see the Capitol building. No problem - Capitol Tours (225-6827) closes down only Christmas Day itself. The free tours start at 9 and leave every 10 or 15 minutes until 3:45. Congress won't be in, but Congress works better in your imagination anyway.

Don't leave the neighborhood at tour's end - how about some Shakespeare after lunch? The Folger Theater (210 E. Capitol St.) plans 1:30 p.m. performances of good William's "Two Gentlemen of Verona." Tickets are $5.50 to $7.50, and the production runs every day except the 24th, 25th and 26th. Tickets: 546-4000.

Local school and church choirs will be a-caroling all week at the Frederick Douglass Home, 14th and W Streets SE. For details on the free program: 889-1736.

William Powell, Irene Dunne and Elizabeth Taylor await you at the Kennedy Center's American Film Institute theater, where there are is a 6:30 showing of "Life With Father," part of the AFFs two-week family Christmas program.

Next? The pageant of Peace - the National Park Service's evening holiday celebration on the Mall - features two junior high school choirs and the C&P Choraliers of Charleston. W. Va., from 8:30 to 9. Sounds will be complemented by some pretty sights: the White House's national Christmas tree (to be lit at ceremonies Dec. 16) surrounded by 57 likewise-decorated trees. The family will be impressed.

More trees reside at the Smithsonian's Museum of History and Technology - 12 of them, to be exact, decorated with hundreds of European and American handmade ornaments for the museum's "Trees of Chirstmas" exhibit through Jan. 2. The eight-foot live trees include representives of Chirstmas in Brazil, Japan, Italy and a French Tree of Paradise. American trees reflect Christmas at different periods in history - including a Tidewater Plantation Tree and a Williamsburg Folk Art Tree. TUESDAY, DECEMBER 20

A perennial ice-breaker - the American Ballet Theater's production of the "Nut cracker" - opens at the Kennedy Center Opera House (through Jan. 1). Showtimes are 7 p.m. Tuesday through Friday, 2 and 8 p.m. Saturday and 1:30 and 6:30 Christmas Day. Ticket, which you'd better seek as early as possible are $6.50 to $14.50. Call 857-0900. Group sales: 634-7201 (The center's group sales office can also help with hotel reservations and transportation arrangements. Out-of-towners can call 800/424-8504).

The other "Nutcracker." that of the Washington Ballet is playing at Lisner Auditorium Dec. 15 through 31. Tickets are $4 to $8.50. Call 362-4644.

Tote your skates and (optional) padding to the ice rinks maintained by the Park Service at the Sculpture Garden on the Mall and at Ft. Dupont (37th St. & Eli Place SE). Good time contingent upon ice. Admission.

Tote away some last minute gifts and stroll in the snow (hah) at Glen Echo Park, with its old stone circular gallery of crafts, open 10 a.m. to 5 p.m. weekends noon to 6 (except Christmas Day).

Step into the past at Fairfax County Park Authority's Sully Plantation in Chantilly, on a tour of the 18th-century mansion decorated in boughs of not just holly but pine, cedar, fruit and berry arrangements. Admission is $1 (children 50 cents), open 10 to 5.

Evening choices:

At the AFI: "Boys Town" and "Father's Little Dividend," 8:30.

Prince George's Civic Opera performs "Amahl and the Night Visitors," 7:30 at St. Martin's Church in Gaithersburg. Call 277-2200.

The Washington Choral Arts Society performs Christmas music - singalongs, carols and classics - 8:30 in the Kennedy Center Concert Hall, with members of the National Symphony Orchestra. Tickets ($2.50-$6.50): 857-0900.

And the Pageant of Peace: Four school choirs and the Prince George's Choral Society, half-hour continuous performances 6:30 to 9. WEDNESDAY, DECEMBER 21

The family wants more wonders. There are several - a live macaw, for one - at National Georgraphic's Explorers Hall (17th & M Streets NW), and at 3 there just happens to be a bonus recital of carols by the National Geographic Society Chorus.

Opening at the Kennedy Center's Eisenhower Theater: "First Monday in October" with Henry Fonda and Jane Alexander, wherein the nation gets its first female Supreme Court justice. Tickets ($6 to $11.50): 857-0900.

Perhaps you're in the mood for James Earl Jones as "Paul Roberson," one person show at the National Theater (through Dec. 31). Tickets ($6.50-$12.50): 857-0900.

Or the Prince George's Civic Opera in a free performance of "Ahmal" at Bowie Arts Center, 7:30. Call 277-2200. Or the National Concert Band of America and Laurel Oratorio Society in joint concert at Laurel Senior High at 8, also for free.

The folks will no doubt appreciate the Paul Hill Chorale's third annual Christmas Candlelight Concert Wednesday and Thursday nights in the Kennedy Center Concert Hall. Tickets are $2 to $8. Call 857-0900.

And again, at the Pageant of Peace: school and church choir, gospel and barbershop groups and the Liberty Bells ensemble from Hartsville, S.C. THURSDAY, DECEMBER 22

Time to slow down, perhaps. Take the family to Georgetown for some walking, and follow a few side streets to Georgetown University, where for nothing more than a polite request at the Information Center in the Healy Building, you can get a tour of the nation's oldest Catholic institution of higher learning. (It dates to 1789, in case the family asks.)

The Reston Brass Ensemble is giving a free concert 8 p.m. at Lake Anne Hall in Reston. Except carols, Bach, Palestrina and Pezel, among others. Call 471-9242.

AFI repeats its double feature of "Boys Town" and "Father's Little Dividend" at 8:30 p.m.

Pageant of Peace bill: Two elementary-school chorus groups, the Capital Choral Ensemble and The Brothers, a D.C. gospel group. From 7 to 9. FRIDAY, DECEMBER 23

The family's beginning to talk about coming back for Easter. Nevertheless:

The Kennedy Center's biggie is its "Messiah" Singalong at 8:30 in the Concert Hall, to kick off its Holiday Festival. Martin Feinstein, executive director of performing arts at the center, will direct you - the audience - accompanied by orchestra and chorus. It's free, usually packed and you'll need tickets. Call 254-3600.

Couldn't get tickets for the singalong? Gather the family 'round the fireplace, tune in WGTS-FM (91.9) and who needs the Kennedy Center? Handel's "Messiah" masterpiece airs at 10 p.m.

Standbys:

"Meet Me in St. Louis," 6:30 at AFI.

Two local gospel groups a children musical and a church choir, 7 to 9 p.m. at the Pageant of Peace.

While you're trimming the tree or wrapping last gifts, tune in WAMU-FM (88) for Fred Fisk's Christmas show, 7 to 10 p.m. The kids can call in to Santa with requests and some prominent Washingtonians remember Christmases past.

"Santa and the Haunted House," the D.C. recreation department's children's musical production, opens tonight at 8 in Howard University's Ira Aldridge Theater. It runs through Dec. 31. Call 673-7635 for details about this and the department's various traveling holiday shows visiting local recreation centers through December. SATURDAY, DECEMBER 24

A night of peace - eventually. Two of many evening church services to consider. the 4 p.m. Christmas Eve Pageant and family service at the National Cathedral, Massachuseets and Wisconsin Avenues NW, and the 11 p.m. candelight service at the National Presbyterian Church, 4101 Nebrasks Ave. NW. CHRISTMAS DAY

If everybody's here, who's to visit? Three alternatives:

"Nutcracker" by the American Ballet Theater at the Kennedy Center, 1:30 and 6:30 performances. 857-0900.

A Shirley Temple double feature at AFI: "Little Miss Marker" and "Wee Willie Winkie," 6 p.m.

Bullets Basketball Night at the Capital Centre - free basketballs to the first 5,000 under-14-year-olds who come to see the Bullets take on Atlanta at 7:35. Tickets are $4 to $9. MONDAY, DECEMBER 26

The Smithsonian celebrates Christmas through Jan 1 with holiday music of old, dance, crafts, puppet shows, special tours and free daily showing of children's holiday films ("A Child's Christmas in Wales," "Hans Brinker: The Silver Skates" and "The Wizard of Oz" at 11 and 2:30 in the Museum of Technology). Details: 381-6264.

The New York String Orchestra, conductor Alexander Schneider's holiday collection of conservatory musicians, performs at 7:30 p.m. in the Kennedy Center Concert Hall. Tickets are $2.50. 254-3600.

Through the 31st the Kennedy Center also plans a children's show, "That's the Spirit," twice daily. Call 254-3600. TUESDAY, DECEMBER 27

The Fairfax County Choral Society gives a free concert at 8:30 p.m. at the Kennedy Center Concert Hall. You'll need tickets - call 254-3600. WEDNESDAY, DECEMBER 28

The Fairfax Symphony Orchestra's free holiday show is 8:30 p.m. in the Kennedy Center Concert Hall. For tickets call 254-3600. THURSDAY, DECEMBER 29

"The Play of Daniel" is a revival of the original 1958 production by the New York Promusica - same costumes, sets and performers - presented tonight and tommorrow night in the Kennedy Center Concert Hall at 8:30. Tickets are $3, call 254-3600. FRIDAY, DECEMBER 30

National Children's Choir is giving a Christmas concert at 8 in the National Presbyterian Church, 4101 Nebraska Ave. NW.