10 - Salzburg
9 - Seattle
8 - Venice
7 - Amsterdam
6 - Portland
5 - Florence
4 - Bend, Oregon
3 - Munich
2 - Paris
1 - Roma
Bend, Oregon probably jumps out off that list. Town of about 100,000 in middle Oregon. It's like Norman Rockwell Americana only with copious amounts of craft beer - 10 craft breweries from the small, like Goodlife, to Deschutes, the 5th largest craft brewery in America. Factor in TONS of fun nature stuff to do - hiking, rafting, canoeing, skiing. Mountains. Forests. Really friendly people.
list is odd in that it's the fun I've had at places, not necessarily order of where I'd want to go again. the mrs. and I are moving to Paraguay in a couple months, so will revisit this in a couple years after we've been to Asuncion, Buenos Aires and who knows where else in South America.
(edit - adding honorable mentions like OP... Vegas, Chicago, Denver)