Hey guys! Thanks for all the replies.
Here are some more mock-ups, this time using the new tiles.

Tom: Seeing as I'm going for tiling and re-usability, I don't think scaling is really an option.
Right now the rock cut-offs looks pretty unnatural, but I'm trying to find a way to fix that while being able to use it in-game in a tiled environment. Also, the cave entrance tile looks pretty terrible right now. But once I get back to my computer with photoshop, I'll try and fix that.