If you're looking at a close airport location, the Hampton Inn-BWI is quite nice. Everything's a little expensive in that hotel district though.

My friend always stays at the Hilton Garden Inn-BWI when he's in town. It's a nice and well kept property.

Tazi suggested the Arundel Mills (Hanover) area and that has a Holiday Inn and a Hampton Inn and Suites. Also right next to some great shopping and activities (Medieval Times, Dave and Busters, etc).