You heard me right, Floor conditions! Small features or tweaks that apply to EVERY room on a specific floor! No need to worry about room-melding problems, and if you're REALLY crafty, you can tie it into the shapes/triggers conditions everything else does!
Granted, this system would most likely deal with aesthetic changes only. Things like time of day or light levels, and weather the pitfalls are dark, or even if they show the lower floor at all. Could be fun to improve the feel of the dungeon!