The Omni is a great, historic hotel located conveniently close to the National Zoo, Adams Morgan and Dupont Circle (walking distance). The Woodley Park metro stop is a short walk up the hill. It's a large hotel with a lot of history, a grand entrance / restaurant, and nicely decorated rooms.
If you ask for the zoo package (whether or not you are going), for only about $30 extra per night you get the free breakfast buffet for up to four people in your room ($20 per person) and free parking (save $35/ night). If you do have kids - or kids at heart - you also get a gift package with some zoo goodies and a stuffed panda.
Rooms apparently vary quite greatly, but in the two times I have stayed there I have stayed in a king room and had a walk-in closet; the bathroom was a bit small, but it had a nice tub. Because of the age of the building, some of the rooms can be loud, so avoid staying near an elevator, an ice machine, or the HVAC blowers (lower floors). Park views are nice.
Excellent price for the area, and the concierge can recommend many great places to eat in and around Adams Morgan.