I have to vote for Hired Guns, of course. Play it late at night in a dark room and turn the speakers up. Also, since you want to play with a friend, it supports coop play
Head over to the Hired Guns Operations Center for maps for all levels.
I recently played through Might & Magic III, and with a walkthrough for the tough parts, it was good fun (I really like the user interface).
Ambermoon is, apart from the short section in the Abandoned Mines,), a terrific experience, although not neccessarily a true classic dungeon crawler.