I'm currently grinding for gear so the XP is a secondary concern. I did library until my mages all had Hypnotic Blade/Illusionary Rod/Mantle of Doan/Robe of Doan, then I did Armory until my Paladin had Herod's head, shoulder and legs, and now I'm doing Cathedral. I have all the drops for my Paladin and 2/3 of my mages have Triune Amulet and Whitemane's Chapeau. Ooh, I just realised I need a Triune Amulet for my paladin too.

Once I have the gear, I'll look again at XP.