WHEN the subway's Orange line crawled out to Arlington, it sparked an explosion of building in the Ballston area, but also led to the more reasonably scaled business boom along the Wilson Boulevard corridor. A big part of that boom was (and still is) the growth in nightlife options, something dear to my heart.

Whitlow's on Wilson is expanding, and seems to be a cash machine, while around the corner, Mr. Days has just openedin the North Highland Street location that once held the Blue & Gold brewpub. Right across the street from the new Mr. Days is the hugely popular Clarendon Grill (1101 N. Highland St.; 703/524-7455), a bar and restaurant that opened three years ago this week, and which after a slow start is seeing its best business ever.

"I'm not worried about Mr. Days coming in," says Clarendon Grill owner Peter Fluge. "I think it's good to have competition. The only downside might be a strain on parking, and that aspect of life around here will only get worse, because I think the Clarendon area is one of the hottest and fastest growing night areas in D.C." Hard to argue, considering the number of cool joints there are to hang out in along Wilson from Rosslyn to Ballston.

Before Fluge decided to supply the world with food and drink, he was a self-described "propeller-headed computer systems geek guy," who had also dabbled in commercial real estate. "I'd lived in Arlington since 1988, and after going into downtown Washington for some nightlife one too many times, I decided we needed something here." Bardo Rodeo, Galaxy Hut, IOTA and Whitlow's were already blazing their respective trails, but Fluge had a vision of a full-service restaurant with an extensive menu as well as a comfortable bar where you could hang out with a drink. "In the restaurant industry its typical that most places have a bar as an afterthought, or just as a holding area for people waiting for tables," Fluge says. "We wanted a bar that had a life of its own."

And it's that bar that's most successful, though Fluge says that sales of food and alcohol run about even. The bar is on a raised triangular mezzanine and is routinely packed. The tables for eating are scattered around the remaining space, the ground floor of a gorgeous 1940 building that used to be several different businesses before Fluge opened it up. The menu is ambitious, but the food has been over-salted and otherwise carelessly prepared every time I've eaten there (maybe they just want us to buy more beer), and the table service has been routinely mediocre.

The coolest thing about the Clarendon Grill is the design, which is built around the idea of a construction site. Scaffolding climbs a wall and stretches across the ceiling. Painted edges of two-by-fours make up the mosaic-like sides of columns. Walls are half painted, but somehow it doesn't look unfinished. It's a unified notion that works, though when the place is crowded with patrons it's easy to not notice.

Fluge says his biggest crowds come in on his charity nights, an idea he hit upon when trying to lure people to his then-new establishment. He contacted charitable event coordinators and offered the place to them, and several (like the Leukemia Society and the American Heart Association) took him up on it. He lets the organization keep the cover charge taken at the door, and the Grill gets the food and alcohol sales. "We average five events a month," says Fluge, "and I'm really proud to say we've helped these organizations raise more than $300,000 in three years of doing this."

Music is another draw for the Clarendon Grill, with weekends offering mainly the kinds of bands that play the sort of music that many of these twenty- and thirty-somethings heard in college. They're jam bands and groove bands mostly (quieter jazz on Wednesdays), and one that plays there the first Friday of every month is the Huge. A four-piece combo that plays original songs that sound like a combination of classic rock and "modern rock," the Huge has developed enough of a following to be releasing its third CD, "Infiltrating the Masses," this week. "I call it progressive soul," says frontman and guitarist Joel Langley, "because it's not just loud guitars. I like to play music with feel and emotion."

The band's free CD-release show is being held Friday night at the Hard Rock Cafe (999 E St., NW; 202/737-7625). Why the Hard Rock? Why not at the Clarendon Grill or Zig's in Alexandria (4531 Duke St.; 703/823-2777), where the band plays the second Saturday of every month? "Heck, it is the embassy of rock 'n' roll," says Langley, and I can't tell if he's kidding. "We just wanted to put out the message that we're serious about what we do, from the recording to the business side of it. We thought it would make more sense to get a high-profile venue, put on a free show and just celebrate the music. And maybe we'll be able to sell some records, too."

Langley is joined by guitarist/singer Michael Feldman, bassist Jeff Cowles and drummer Greg Berger, all of whom play their part in promoting the band, booking shows, designing the Web site (www.the-huge.com), creating artwork for the CD and posters, etc. "We're extremely well-adapted as a band, not only as friends but as business partners," Langley says. "Since we do everything ourselves, the fact that we're still friends and hang out together is amazing. We're definitely very much family at this point."

BLUES GETS THE BLUES

Try phoning Capital Blues, the little townhouse nightclub and restaurant on Connecticut Avenue NW, and you hear: "The number you have reached has been temporarily disconnected." That's an ominous sentence. And just how temporary? Hard to say.

About a year ago, I wrote about how an employee of City Blues, Chuck Rogers, had purchased the club from its founding owners Jimy and Lu Ann Brown and changed the name to Capital Blues. But over time, what was once a musician-friendly club with nice atmosphere if mediocre food, became (according to many musician pals) increasingly disrespectful to musicians, developed a sour atmosphere and still served mediocre food. Sounds like a bad recipe for success.

Rogers closed his doors to go on vacation a few weeks ago without telling the musicians who'd been booked to play, and when he returned, closed them permanently. That took place last week. One source close to the business says that Rogers (who did not return phone calls) just didn't have the cash flow to make all the ends meet. A sad end to what was once a nice little joint.

JAZZ GETS THE BOOT

For jazz aficionados, Monday nights at State of the Union on U Street NW have been a haven for daring and creative music for five years. Almost every Monday during the past half-decade, saxophonist/composer/arranger Peter Fraize has led his trio (and dozens of guest musicians) through an incredible musical wilderness, exploring places few Washington performers are willing or able to go.

After this week, those explorations on U Street are at an end, with State of the Union's owner opting for Monday Night Football over live original jazz. "I don't begrudge him trying to do what's right for his business," says Fraize, "but giving me 10 days' notice after doing this for five years -- that's weak, is what it is, and that's what I told him."

Fraize says that being replaced by televised football is particularly galling but admits that if not for the NFL, the owner would probably have just closed shop on the unprofitable Mondays. For his final gig this week, Fraize says he's calling around to all his musician friends to come sit in with his trio (bassist Steve Zerlin and drummers Leland Nakamura and Francis Thompson, who usually alternate Mondays but who will both be there this week).

Look for Fraize to resuscitate the jams sometime in December, on Wednesdays, at One Step Down (2517 Pennsylvania Ave. NW; 202/955-7140). "We'll throw a fifth anniversary party," Fraize says, "but combine it with our relocation party."