personally? i would actually channel a lot of that disney feel and make it kind of... like a city version of the magic kingdom park (or the zootopia where they had all the different biomes oops). you have sections of the city that's the fantasyland, sections that are more for the animal kingdom type, and then a few other ones like the futuristic and such. maybe even make it that this city was built to house the characters after they all came to life and all that?

....... look man, i've just been playing with this idea for a little while now (since batim finished actually), and i really like the idea of it, so i'm more than happy to pass it along to a good home where it would make sense and be super fun to play in, so. yeah.

I don't know if you're still in need of advice on this, but I'd say organization is key. For me, personally, when I go to sites with separate locations (whether it's a roleplay taking place on opposite sides of the world or simply different biomes of a city, it's good to have clean, clearly shown separations between them especially if the differences are stark and can mean wildly different outcomes (like, say Cinderella goes to the Animal biome and gets face to face with Simba. That wouldn't be particularly pretty.)

It's really just based on what you'd prefer. If you'd like it set in an actual fantasy setting, go for it. If you want it to be a modern au, go for it. The most important thing is what you want in a site. Right after, of course, organization. If you want different 'biomes,' in lack of a better word, to interact pretty much on the daily, I'd say just make them different boards with landmarks spread out across each of them. If not? Different categories is the way to go, especially if it's going to be a sort of "choose your side" style faction thing. Way easier for roleplayers to find what they're looking for, that way.

Sorry if this is late or didn't help at all xD just thought I'd pop in.