DH, CC, AV are the same. 2 bosses and extremely linear.

What I would desire: 1 big dungeon. 5-8 bosses, in several wings. Extremely hard final 2 bosses. Wins are guarantee drops on the final bosses, but of several variety. No time restriction. Traps, aggro concerns, additional mobs, visual depth to the dungeon, exploration etc. Allows for the time sink of farm, but replay value for wanting to beat a final, hard boss.

An example would be RIFT's Hammerknell. If I am not mistaken, it took over 3 weeks for the final boss to be downed in a rather large dungeon.