How about Cologne, Germany? 1m inhabitants, lots of college students, gay capital of Germany, vibrant free and experimental jazz scene but also lots of funk/soul/function gigs, media outlets galore, one of Europe's best professional radio big bands (at the moment lead by Bob Mintzer), excellent music college, close proximity to Belgium, the Netherlands, France (3 hour train ride to Paris). The visa process is bureaucratic (it's Germany, after all) but as an American you enjoy certain privileges (my wife is American). Lovely river Rhine. Housing is expensive af, but as most Germans rent instead of own, you don't have to put down serious cash right away.
Oh, and of course big touring acts pass through all the time.