One thing I would like to see is a chance of getting clues when you rescue a survivor. After all, who knows if they lived through some of the horrors described by some of the clues you find? Survivors seem like they would be a good source of information.
Also, given the current rareness of puzzle rooms, I really don't want to see puzzles that you can permanently fail. That just doesn't sound like fun. The only puzzle idea that comes to mind right now, however, is a sort of ricochet puzzle. You'd need to aim a spell at the right angle so that it gets through the reflectors, and deflectors, to hit the switch on the other side.