I would like to see more horror characters like werewolves and vampires, mummies and witches, ghosts, Medusa, giant snake, swamp monster, goblins, trolls, spooky clown, and Bigfoot.
Also "haunted houses", Gothic cathedrals and spooky castle prefabs.
Trap doors on the floor that you can fall into, walls that swing open when you tug on a hanging candle/torch, a "bookcase" door that opens up revealing secret passages.
If possible, prefabs of hills (that extend up a couple layers) and ponds, streams, rock retaining walls, and other outdoor terrain.
Egypt themed packs would be cool too; pyramids, sarcophagus,etc.
"You're from Wisconsin... artificial light is fascinating to you."
-Bill McNeal, News Radio