It might be helpful for you to define in the area. The Marriot is downtown and there are a number of good places to eat.
(1) The Red Sage -- high end, pricey, but very good yupee mexican. Great decor
(2) McCormick and Schmidt -- great seafood place. Good menu of single malt scotches. I always see famous people there
(3) The Talbard Inn -- very, very cute romantic place. Good french/Italian food. Nice wine list. It is a great date place because they have these big comfy chairs where you can sit and drink wine until all hours of the night. Last time I was there Joan Baez broke out her guitar and played for a while (but don't expect this)
(4) Jalios (i'm not sure that's how you spell it) Is a good spanish place with lots of Tapas
(5) Old Ebbit Grill -- Classic DC place. Good food, nice atmposhere.
I left about 4 or 5 out, beacuse these are my favorites. Outside of downtown -- Georgetown, Adams Morgan, etc. There are lots of great places.
My favorite place is "1789", it's about the best food I have ever had. It's abougt a 30 min. cab ride from where you are staying.
There alot more, but this is a good start. Happpy festing