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That would be great! The Ghost Town was originally meant to be an above-ground minibiome in the desert, though I ended up deciding against it since the above-ground desert isn't terribly large and it would probably end up cluttering up the surface. And also because I love underground minibiomes, but that's just me.
They look great so far! I'd say to just go at your own pace and sprite whichever one's you'd like. There's no rush to get all the sprites filled or anything, so you can choose the order you want to go in. I might end up spriting a few of my own too, since it looks like this suggestion is getting pretty popular again.