AROUND 1900, in Cleveland Park and Chevy Chase, great big expansive houses were built to hold families with lots of money, lots of children and lots of servants. None of us have as much of any of the three as we used to, but the houses are still among the pleasantest in town. In recent years, most of the houses have been remodeled to bring in modern ideas about light and air. Several will be on display in two house tours next weekend.

The Chevy Chase Village House Tour and Tea from 11:30 a.m. to 5:30 p.m. Saturday will benefit the Citizens coordinating committee of Friendship Heights Inc. The Cleveland Park House Tour next Sunday will benefit the National child Research Center.

The Max Kampelman home, one of those on the Cleveland Park tour, is that sort of house everyone remembers. It has a real cupola topping a polyagonal three-tiered porch, a souvenir of the Japanese fad of the turn of the century, and, according to the local legend, of the world tour by the people who built it.

In any case, it is a wonderfully romantic house, with its tile roof, all settled into the side of the hill. The house has not only kept its cupola and tile but also an acre of land, which gives a setting suitable to its majesty.

The Kampelmans have lived in the house about 20 years. And their three girls and two boys have had a childhood anyone might envy, climbing up the ladder to the secret place between porches, and inviting only their best and truest friends to climb all the way up the ladders to the top where you can see all the world that's worth seeing.

About 10 years ago, architect Hugh Newell Jacobsen designed a playroom for the house. It was to be polyagonal as well, until the bids came in ($30,000, a fortune back then), and then everyone agreed a square room ($10,000, multiply it a number of times to guess what it would cost today) would serve just as well, even though it wouldn't be as funny. The room is wonderfully versatile and seems to grow as the children do. There's space around the fireplace to sit. The sliding glass doors and flower sink have become a greenhouse for the gardening daughter. And no one minds if you bring in your bicycle and park it at one end. From time to time, there's a great flurry of straightening, the bicycles have to go out, and the Kampelmans use it as a partyroom.

Not that there aren't lots more spaces to party. There's a deck which encircles the back of the house, from parlor all the way around to the playroom. Underneath, it serves as storage for all those things you need to keep up an acre of ground. On the upper level, it's a fine place to sit and sun.

The house's greatest glory, after the three-tiered front, is the swimming pool, a generous 20 by 40 feet, deep and wide enough for diving. At one end is a visual joke which is immensely practical. Swimming pools in the classical tradition have at one end three or four decaying pillars, preferably with wisteria draped over them. so Jacobsen, who for all his alleged modernity is really a classicist at heart, designed for the end of the Kampelman pool a pair ofcabanas with a bath allcolumnar in shape.

Inside the house, the Kampelmans, to-Jacobsen's design, turned the original butler's pantry into a fine mudroom and powder room between playroom and main house and made a big comfortable kitchen out of the original dining room.

The library became the dining room, and the living room acquired the books and a fine library ladder. the house is furnished just as it should be in high Victorian style with a myriad of objects from first one place and then another. Among the most handsome pieces of art are the two fine color portrait photographs of the children by Judith Gellert, who now writes children's books.

The Noyes Thompson Powers house, on the Chevy Chase tour, is a far more formal house. It sits squarely on the street, minding its manners.

The house is in the process of being remodeled by the Powerses, to a design by architect Walter Ramberg. The Powerses bought the house last April and moved in august. Since the middle of September, they've had a steady procession of workmen. Mrs. Powers has given, she says, "six months of my life" to the project, and has subcontracted out the rest of the jobs -- including repairs after a recent flood in the basement.

"We asked Walter to open up the house for light. We had seen a modern house he had done, and we loved the way the house seemed so bright and airy. So we asked him to do our house over for us to try for the same feeling."

Ramberg accomplished the task by putting in banks of sliding glass doors in three groups in the living room. Mrs. Powers, on the advice of decorator Mary Beth Bisselle, painted the living room, complete with its beams, and the front hall a brilliant true white with beige upholstery.An angled deck meanders around the back of the house, past a small sitting room, which also has acquired sliding doors, past the butler's pantry and to the kitchen.

The formal dining room, with a chair rail made from moulding rescued from the living room, even has a secret door, actually a panel cut in the wall, leading to a surprise morning room on the east side of the house where Mrs. Powers plans her day. another end of the dining room has lighted glass shelves, and in between, a marble counter for serving.

Upstairs, the son's room has one whole wall covered with a 9-by-12 map of the world, bought (for $7.95 a section) from the U.S. Army Map Service.

Besides Mrs. Powers's work, the remodeling cost roughly half the $175,000 price of the house. But the house next door is up for sale for $350,000.

Tickets for the Cleveland Park tour are $5. For information, call 363-8777. Other houses on the tour are those of: Mr. and Mrs. James Rowe, a white frame house with wisteria; Ann Perrine Hodgdon, whose house has iron work by Frank gichner; Rep. and Mrs. F. B. Rooney, who have a large dining room overlooking Tregaron; Lou and Di Stovall, house and print studio; Mr. and Mrs. Phil Harter, whose house is remodeled to a design by architect Harry Montague, with a circular stairway and many skylights; Mr. and Mrs. William McDaniels, whose house, redesigned by architect Dickson Carroll, has a master bedroom suite with eight skylights; and Patricia and Terrance Sheehy, whose house has turrets, balconies and a gambrel gable.

Among the houses on the Chevy Chase tour (whose owners asked that their names not be given) are: "Toad Hall," built in the 1910s; a yellow frame colonial with a false skylight; a Victorian farmhouse, now with a Jacobsen addition; a 1906 Cape cod miniature, designed by architect John Lane for himself; an 1895 stone cottage with diamond-paned shutters; and a Victorian family house, recently redone by the decorator/owner. Tickets for the tour can be bought at Chevy Chase Village Hall, 5906 connecticut Ave. For information call 654-6062.