Hahahahahahaha, USMC I just saw your avatar. Oh man, classic.
I will also second, errrr... third the Crystal City Marriott. I've stayed there a few times and it was great, but like I said, I stay at the Hilton Garden Inn now because it is close enough to the things I do in D.C. Or if you have enough BDCP money that you don't know what to do with, the Mandarin Oriental hotel is great. Close to a metro station which is good because it ain't that close to anything else.
There is also an old hotel that was refurbished near Georgetown, I forget the name but it is nice (and expensive).