If you're doing foreign cities, I'd recommend

*London (Grosvenor House or Ren Chanc Court are the top 2 here, with people also liking Grosvenor Square),

*Amsterdam (unlike USI I'm a huge fan of the Marriott over Ren; there are plenty of threads dealing w/ both re: Ams, as well as the London properties, so search is your friend)

* Vienna (Marriott on the ring across from the Stadtpark).

All 3 are lovely cities, have a lot of culture/museums/theatre/concerts/parks, and are nicely positioned for day trips outside of the city as well.

Cheers.