if you are above 80, dungeoning with random is good enough. anything lower than floor 30 dung with friends in c6 small. you get more xp than doing 1 of those in a large.
So far when I solo I average between 6-8k xp, but I'm only level 59 dung on the furnished floors. Runs take 15-30 mins depending on how many resources I gather.
I have started to only pick up food and cash, not bother with resources. Best dungeon so far was 7.9k xp in ~9 mins. I'm mainly going for tokens, don't really care about dung itself.