As a brand Novotel is positioned much higher than Ibis but much of this is in hotel services (conference rooms, 24 hour room service) which may not matter to you. The furnishing will be nicer, however the cheapest hotel in NZ tends to be clean and comfortable and adequate. Location is basically the same (CHC is very small, a few blocks). I usually stay at the Crowne Plaze which is considerably more expensive most of the time, but would be OK with staying at the Ibis.