Since exeriors are so large in size, they hinder the expansion of a server, perhaps there is a way to make a feasible, yet still attractive, thick woodland tileset for interiors. After all, caves are interiors and they can be rather, well...concave and convex.
Anyhow, I would love for someone to make a tileset for very thick woodland areas as to help builders keep very large forests, but they'll be considerably smaller in size.