When i used to train dunge, w117 was the way to go(even though it lagged like hell). I did floors 1-20 small,21-30 med, 31+ large. I always did them in random teams, never soloed(horrible xp imo). I always had a 5 man team, a few low-level players to keep the monsters and bosses as low lvl as possible. Make sure you dont reset the floors until you have done every single floor you can do! This will determine your xp. Oh and i mostly rushed floors 1-30.