I don't think my town has any specific theme. I'm pretty much just building PWPs as I get ones requested that I like. I guess there is a sort of "foresty" coastal town feel going on. I have a lighthouse, a whole bunch of trees everywhere, and a bamboo patch planted next to a zen bell. I'm planning to build a mini little Tokyo in one corner of my town, where my train station and town hall are, since I have the Tower PWP unlocked.
Mine's the "Does this look good? Eh, I guess. This other thing might work better, though. Well, I already paid for it now, might as well keep in there." theme.
Really, though, I don't have a theme at the moment, and I don't think I'll really be aiming to stick to one.
Since I have a Stark wolf flag and my town tune is the Game of Thrones opening theme, it's become a bit of a modern Winterfell sort of deal. Lots of blue roses in front of my town hall. But other than that, I tried for the modern theme even if some PWPs are not modern-ish.