If I had to choose a city in Unova to live in, it'd definitely be Nacrene city. That looks like it would be an amazing place to live! So calm and laid back, and surrounded by nature while not being too far from other larger cities. Other than that, I think my favourite place is Village Bridge, though I'm not quite sure it counts as a town. I love the music there!
I agree, it would be nice if there was more incentive to get around and really explore once you finish the story. I just seem to fly between Lacunosa, Striaton, and Nimbasa depending on whether I'm leveling, breeding, or battling. There's really not much reason to go anywhere else.
And I completely agree about the Black City/White Forest areas. I was really looking forward to White forest, but when I got there it was basically empty and useless because I took my time with the main game. Cool idea, but it shouldn't be quite so dependent on interacting with an opposite game cartridge. I really felt shortchanged by that.