Well, while looking through the Interior list for GSF Paradise in the Mission Editor, I came across these..
This ones called VeniceNone of the buildings are enterable, but there is a bridge across the big cbrown towns.
Its the only one though, which doesn't make much sense.. More pictures of "Venice"
This is "FloatingCity"Its right below the "FloatingVillage" interior
There's two parts to it, Across a big gap.
Interior of the second part
This one's called CityTest, or something like that..The interior of all the brown buildings are like shops.
Theres a two story brown building. The bottom floor is like a shop, and the top floor is empty.
There IS a deck though.. Heres the bottom Floor
This one's called TC I'm not sure if its in Paradise, but if it is, I haven't found it.
It Probably stands for Treasure Chest. Dur.
This is "House1"It has no interior, its the same on all four sides.
tl;dr: Theres unused interiors in the Paradise interior list in the Mission Editor.
Post your thoughts or whatever. Thanks for viewing :D