Rotorua would be a bad bad bad idea ... Given its actual location it would not suit any tour operators as tours tend to start North then go south or vv. Same with DIY holidayers then fly in to AKL and go South and fly out of CHC or ZQN ... With Rotorua sort of being in the middle it would mean alot of backtracking! and I dont see many people flying to NZ just to spend a w/end in Rotorua.