After having easily fixed my earlier gripe with winter-time trees, I ended up making these:
If you're still taking requests for additional tiles, though, I realized I'm really, really, really missing two things: Arabian Nights-styled desert structures/cities, as well as jungle tiles (and cities/steuctures, if possible).
I have a map in mind that I'd really like to do in this style, but making such tiles from scratch is simply beyond me.