I can think of some exciting features. Different doorways or major entranceway. Sewer style maps. Wilderness maps. Setting a % mix of sewer vs wilderness vs dungeon. Rounded rooms. Layers with index key for each level of a linked dungeon with an icon/location to show links between dungeon levels. Also cave / rough hewn style walls in addition than straight. Excellent work as ever! How about adding a keyed dungeon entrance beneath buildings in your town/village generator.