I'd still recommend my own alma mater, Macalester College, here in St. Paul, Minnesota. Small, liberal arts, in an urban environment (but urban here is a lot like suburban in some other places), high academic standards, with a long tradition of liberal-to-radical politics and internationalism. (Walter Mondale and Kofi Annan are alumni.) It's expensive, but also well-endowed, so lots of scholarship money is available. There are also several other small colleges and one very large university in the Twin Cities area that allow students to enroll in each other's courses, use each other's libraries, etc.