Well in my opinion:
1. Dungeons with a great back-story is must. Whenever I enter a cave or an old ruin, I explore it down the smallest detail to see what I can find, and if I come across
an old journal or a note, it makes the experience a thousand times better!

2. I suppose this links in with number one but my favourite dungeons in Skyrim are the ones which have specific quests related to them. Like I said, this provides a
back-story about the location and makes it a longer lasting experience. < The last part sounded like some sort of six ad!
3. Ones with lots of loot to pick up! I.E Gold, Enchanted weapons/armour and Ebony Ingots!
4. Different enemies all varying in difficulty
5. Dungeons that are non-linear are also amazing, ones which contain all sorts of deadly traps and have plenty of twists and turns.
