San Bernardino, CA
Not exactly known as being a "holiday destination", but it's certainly one of mine, since I have a lot of friends there. Outside of the ugliness that happened and the general sketchiness of the downtown area, the mountains really are amazing.
San Diego, CA
To this day I think San Diego is one of the most amazing places I've been to. I know people have a tendency to go to Los Angeles and San Francisco instead, but I always urge my non-American friends to go to San Diego.
Seattle, WA
Awesome city with a great music history. Also has a great market (Pike Place Market). Only downside of Seattle is that it doesn't have an NBA team (thanks, Oklahoma City).
Boston, MA
I went to Boston in December of 2013. The most I had was a hoodie, pair of jeans and a pair of Vans kicks that were falling apart. I'm surprised I didn't freeze. Great city, though.