I did verify via Steam, and it said everything was kosher. After rooting around in the files a bit, I found one called "Layered Music" with a bunch of MP3's in it. After skimming through them, I realized I really did like quite a few of the themes. But there were some, that if combined together, would be jarring for me. (And there is also one called silence, which could explain why sometimes there is no Music for me on the World Map.)
So, I pulled two out from the layered music file and that seems to have made the music more pleasant for me. I have no idea if it is random chance though, or if I actually changed something with the game.
Cheers!