Mark:

Try looking at the Washington DC Convention and Tourism Corporation Website: www.washington.org.

There are 2 places to check:
1) Click Visitor Information and then find the link at the top called "Where to Stay." You'll probably find SOMETHING, but it won't be like the Westin Grand, and probably won't be in the City. You'll probably have to go out to MD or VA.

2) The other option is to check out their Members section, under accommodations. You'll find a category that says something like accomodation services, and it's been my expereince that they've been able to find rooms when few others could.

I hope this helps.