It was deliciously decadent. My husband's law partner thought he was in New York; our house guest didn't know where we were; I left my mother in the dark, even. Now that we're home without invasion of our secret destination, the truth can be known: We went to the Georgetown Inn.

At 12:10 on a Saturday afternoon, we left our native Dupont Circle apartment and drove the mile and a half down P Street to our weekend retreat. Even with Wisconsin Avenue traffic and almost disastrous car trouble, total lapsed time was a scant 20 minutes. It beats fighting the Bay Bridge in summer.

At the Inn, our car was valeted away, not to be seen again till the following day. Reservations for our $60-a-night double were in order, but our room wasn't made up since checkout time wasn't until 1:00. The immediate available option was an upgrade (isn't it always?) to a "room with an alcove and king-size bed" for an extra $8. Without too much thinking, we said "yes." It was worth the extra bucks. In fact, it was so nice, we decided to share it with friends, and invited another couple, who promised to keep our cover, over to watch "Saturday Night Live"; they promised to bring the corkscrew and we'd provide the wine.

Not to downgrade the metropolis of Georgetown, it wasn't our first choice for a weekend away; it didn't even rate number two. Original plans called for a bang-up time in New York City; theater, a stroll down Fifth Avenue, Bobby Short at the Caryle, and Sunday bruch at the Plaza. A room at the Algonquin was guaranteed reserved and it was to be our big fling. Then we started to add up money and travel time, and just couldn't justify the expense. So on the Thursday before the weekend in New York that wasn't, I made a few last-minute attempts to get reservations not too far from D.C. - either the Maryland Inn in Annapolis or the Robert Morris Inn in Oxford. Both were booked solid.

But the Georgetown Inn turned out to be a good choice. After we checked in, we decided on the obligatory promenade up Wisconsin Avenue, with stops at Au Pied de Cochon for lunch, Doc's for my husband's after-dinner cigar, and a pit stop in the Georgeown Coffee Shop to replenish gourmet items not stocked in my neighborhood.

I think the subconscious fact that we were spending $68 for the night to be in Georgetown helped us enjoy the area more. Next, it was "where should we go for dinner?" After several menu perusals, expanding our walk to M Street, and a "Bonjour" from a monkclad waiter at Le Cellier des Moines, we decided to dine at Jour et Nuit. We'd always wanted to try it, but usually overruled it because it was "too far away."

Later in the afternoon, back at the Inn, we gave the room a closer inspection. The four-poster king-sized bed took up most of the space, but there was ample walking room in the "alcove" around the sofa, large stuffed chairs, and a writing desk. The bathroom had two sinks. Good plus. All in all, above average room, even by our expense-account travel standards.

What next? We looked at the entertainment section of the paper, and discovered that "Around the World in 80 Days" was playing at our favorite theater back downtown, the Circle, and decided to go. Twenty minutes to showtime. What's the quickest way to get there? Eliminating retrieving the car from its space, we decided to get a cab. When we walked out of the Inn, there was a bus at the stop directly in front of our hotel; it was waiting for us and going our way down Pennsylvania Avenue. We took it and arrived at our destination with just enough spare minutes to get a new book of 10 tickets and some popcorn. Phileas Fogg, Esq., and Passepartout made it around the globe on deadline, and we met our 9:30 dinner reservation after cabbing back to greater Georgetown and showing and changing. Dinner was terrific: I splurged on rack of lamb and Rob got veal.

Back to the hostelry and a special treat - Bob and Ray, those old New York favorites, on "Saturday Night Live." Our invited friends whistled at the splendor of our room, but we kicked them out at 1 o'clock anyway, right after the show. It was our weekend away, after all.

Sunday morning demanded another tough decision: where to brunch to cap the weekend. We skipped the pricy champagne brunch at the Inn (which looked pretty good) and instead crossed the street and went to Billy Martin's. An older man, who looked like he got his training at Duke's, served us our bacon and eggs and coffee. Another short walk on the Avenue, and it was time to get in the car for the trip home.

All was in order at our Dupont Circle villa and we felt really refreshed, as if we'd been somewhere far and away.

Walking up the three flights to our Q Street apartment, we smiled. As always after a trip, no matter how brief, it was good to get home. CAPTION: Picture, THIS IS A NICE PLACE TO BE A TOURIST, EVEN IF YOU LIVE HERE. By Ellsworth Davis.