I like the idea from the Beyond the Grey Mountains website of having monster themes in a dungeon. At the start of a game BtGM use a monster token (similar to a character token) in order to determine the monsters they will encounter. It breaks up the inconsistencies of having trolls, chaos warriors and skaven in adjacent rooms (which is a little unfluffy for my taste too). I felt this may mute the element of surprise for play throughs so play to do some test games drawing two tokens
So I have been collecting miniatures for filling entire dungeons on a dual theme, so having enough variety of miniature without having to draw cards from across the entire range.
Chaos (daemons, beastmen and warriors)
Orcs and gobbos
Miscellaneous monsters - large and small
I've also worked on building and basing for some undead.