I had really fun too! And I learned a lot from listening to you all.
Personal mode: I was born in 1981 and the games of my childhood are the Zelda of NES and SNES as well as Secret of Mana. So my imagination when I hear about "Town Music" is very much linked to the games of that era.
I was pleasantly surprised by the very varied genres that were proposed and that work very well to illustrate a city.
To answer your question "What makes a good town theme?", I would say two things:
1 - it should not be boring, if you have to stay talking with NPCs for 20 min, the loop should be long enough that you don't want to cut the sound
2 - that she is forgotten so that she colors the city without drawing attention to her
That's it, I don't have anything better :D
What about you?