What about irregular caves with winding passages?




Okay, now you've impressed me again!
One thing I'd add to this discussion- though it looks like you're probably already on the same page- is not to add in arbitrary features like dead bodies, magic circles, etc. Those REALLY limit how useful a lot of Dungeon Tiles are.
If these do well, you might consider adding an urban/city set.
Good luck!

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.