Well since I happen to work at both, I can give you a little insight...
Ditto to everything ddoll said. Also, by the time you arrive in December, the full renovation of the lobby areas at both the Swan and Dolphin should be complete (they are scheduled to be complete in September--it's kind of chaotic right now). It's going to be quite spectacular. And the Dolphin lobby is apparently quite amazing during Christmas time with a giant Christmas tree in the middle of the lobby area.
I work mainly at the Dolphin, so be sure to say hi when you come visit!
