Reverend Teri had a magnificent idea for yet another place to stay in Europe: monasteries and convents! It may at first seem like staying with the monks and nuns would cramp your style if you were a twenty-something romping across Europe, but remember: The monks INVENTED beer! Plus, I hear that the monks are known for eating well (The cliche isn't "skinny friar," after all) and they're apt to have a great deal more to tell and share about the area. The more I think about it, the more I like the idea. Plus, it promises to add a new and interesting dimension to the "Your place or mine?" discussion. (<--- If you are a parent person, I'm only kidding.)
*PS: Apparently the Basilica of Sacre Coeur de Montmartre (oh, THAT one) has a retreat house/pilgrims house. Could be interesting!