The Shade King - thank you for bringing up UMass Boston's program. I'm an alum of the MA program there, and I agree that it is excellent! There are also plenty of opportunities to TA, and the program itself is quite affordable.
Sillyrabbit, you might be interested in checking out this thread: http://chronicle.com/article/NRC-Rankings-Overview-/124700/. American Studies programs aren't officially ranked, as are PhD programs in other fields, though. I also don't think that ranking is as important as fit, as American Studies programs can--and do--have completely different approaches. They are really all over the map.