Thanks for your advice - I have already done that to an extent, and come up with Princeton, Georgetown, GWU, UVA and U Texas-Austin, which I think represents a reasonably fair spread of schools ranking wise (although maybe not?). I don't want to apply to too many schools, but I think I could add Duke to that mix.
I was really just fishing for any extra advice that might be floating around from people who knew off the top of their head where the best places to study this kind of thing was - and in particular, for any advice that I wasn't getting by trawling through websites by myself.