I'm am currently working on my first MCEdit project, Adventure time's Land of Ooo. It contains the following locations and hopefully many more to be added in the future.
-Town of Thieves
-Mallow Tea Ceremony
-L.S.P.'s Hobo camp
-Hole at near center of the world
-Swamp of embarrassment
Just watched the first SwimmingBird941 video on this and I must say it does look pretty good so far.
^ (His video description also has a link to the texture pack, and Gulliver Mod used for playing as Jake)
Not sure if these are the latest versions, but I dare say so if the Project is on Hiatus..
As for it's flat-map foundation being "a problem", most cartoon scenery usually is flat, with protruding hills, trees, and stuff anyway. That aside, if it really is a big issue they can quite easily resolve it, with most editors such as WorldEdit having the ability to save previously created structures to schematic files for pasting into any new map (they come with Cylinder, Sphere, Wall, and Ceiling schematics as examples of this)..