Sit down in a bar or restaurant in Old Town or Georgetown or downtown and order a glass of wine. Chances are you'll get the "house" wine. Now, that wine is no more the reserve of that house than of your own condo or castle. In most cases, it's an inexpensive (oh come on, cheap) wine available all over town. If you're a regular wine buyer, you'll know that the house wine is the most overpriced item on the wine list. But, on the other hand, it's also the least expensive wine on the list. It's a dilemma. Do you splash out on a whole bottle, in order to drink something interesting, or do you settle for a glass of the house plonk?

There must be a solution. There must be some way in which we can go out and have a glass of decent wine without feeling ripped- off. I'm still putting my money on the wine bar concept: a place that specializes in wines, offering a selection by the glass and bottle. Not attempting to live by wine alone, I would also like my ideal wine bar to serve light meals, especially at lunchtime. So I'd expand my definition of a wine bar to include those caf,es and restaurants that offer at least five or six wines by the glass.

Starting below and continuing next week, here's a look at some of our area's bars- caf,es.

The Carlton Wine Bar, Sheraton-Carlton Hotel: Opened in October 1979, the first successfully established and longest running wine bar in Washington. Calm and sedate, more suited for a discreet chat with a new client than a night on the town with an old buddy. There's a well-balanced list of wines by the bottle and a weekly short list of wines by the glass. Champagne and America are well- represented, and there has been a creditable crack at finding mature reds from Bordeaux, but, as elsewhere, Burgundy is neglected.

Prices are higher than average. You're paying for the classy setting and for the classy service, but those who sip at the Carlton do so because they value these declining commodities.

Starting this summer the Carlton is to be enlivened by weekly special events, including vertical tastings and festivals. It is also the home of the newly launched Champagne Connoisseurs Club. Linked with Les Amis du Vin, the club meets once a month to "evaluate every French champagne currently available on the American market."

The Carlton's biggest drawback is that it cannot be used as a wine bar at lunch. To sit in a comfortable chair with a glass of wine and a wedge of cheese and crusty bread would be a relaxing way to spend an hour. The cheeses and p.at,e that are available seem less appropriate at 4 in the afternoon or 8 at night. However, there is hope. The quality of the cheese and p.at,e is about to be improved, and seafood, fruits and nuts will be added to the menu. Open Mondays to Fridays, from 4 p.m.

From the growing list of restaurants that serve more than a couple of wines by the glass, Henry Africa, 607 King St., Alexandria, has at least six, including a champagne. The selection changes frequently. A wine cellar is under construction, and the regular list of about 155 wines will be expanded to 215.

Tunnicliff's Tavern, 222 Seventh St. SE, has the trappings for being an authentic wine pub. However, although there a several wines by the glass, served from the bottle at your table (a nice touch), it's not certain that the management intends it to be a specialist wine place. A pity. With its Edwardian mood, a long bar that has plenty of standing room and the sociable neighborhood of the Eastern Market, it could be a winner.

For less casual occasions and a glass of wine or champagne, with a snack if it's lunchtime, the Garden Terrace in the Four Seasons Hotel, 2800 Pennsylvania Ave. NW, is one of the prettiest, albeit pricey, settings in town. An outdoor cafe, the Plaza, has been opened for fine weather days.

Next week: Suzanne's, Park Place Cafe and La Colline.