I'd just like to add a note - I was studying in Berlin last quarter and yes, the airfares across Europe are cheap, but they require a fair amount of planning. This may be more of an issue with 10-week terms (planning 4 weeks in advance is, well, just about half a term later), but it's still an issue.

It may be best (or cheapest) to do city-hopping on the continent right before or right after the program.

And definitely lonely planet... buy them in the States; I found many travel guides marked up when getting guides for trips in the bookstores!