When you retire, beginning to have time on your hands, that is the time to be in the center of things. So it makes sense to have a retirement home in the city, with two florists, two markets, three drug stores, five banks, two cinemas, a library and a community center within four blocks. That is where Chevy Chase House is located, and less than a mile away is the Friendship Heights shopping bonanza. Chevy Chase House also provides free limousine service to take you elsewhere - downtown, to the Kennedy Center, or to visit your children who don't live in the center of things. And it brings the outside in, with lectures, night club entertainment and Sunday afternoon concerts. The management is planning an outdoor cafe for continental breakfasts or wine and cheese; it has a library and chapel, and will send to your room a manicurist, a masseuse, a nurse and breakfast with the morning paper. Claiming to "cater to the group between 60 and 95," Chevy Chase House has decorated its public rooms with antiques, and keeps fresh flowers on the dining room tables, which are set with pink cloths. Meals include salad bars and dessert carts, even wine. And for snacking, the apartments have complete kitchenettes. Maid service, nursing stations on each floor, intercoms in bathrooms and bedrooms. Handrails in the halls. Chandeliers in the lobby. Chevy Chase House has hardly neglected a need. But in case you are not sure, you can rent a suite for the day, the week or the month, furnished or unfurnished. Suites range from studios to two bedrooms, from $36 to $53 a day unfurnished ($4 extra for furnishings) and include meals, maid and nursing service, linen service and limousines. It would be nice to