United Frequent Flyer miles... best use for Europe (?) travel in May?

We had a trip that was busy but lots of fun. We visited Rome (4 nights - terrific VRBO apartment near Plaza Navona) and Venice (1 night - excellent hotel recommended by Rick Steves book - Hotel Capiello) and sleeper train to Munich (4 nights, Hotel Amba).

Feel free to PM me if you have questions about those places.