Some stuff I found out while accommodation hunting for the march

[liberalitch]

Just pick a place near the metrostops....
Crystal City (Marriotts, part the axis of evil but clean, reasonable {$119per night, junior suites $240} and RIGHT above the metro and a mall with good burgers and sushi)
Pentagon City,
Olde Town Alexandria (Embassy suites is pricey but has a free happy hour and breakfast)

http://www.lodging.com

This is a good place to start..... Pick a landmark so that it doesn't list hotels out in bum-fuck

On edit: or you could just sleep on a metro grate..... apparently that has become more popular since bush has been in the whitehouse..... as more people seem to be doing it.