Te Papa museum was quite good
Nice to go up the cable car and walk around the mountain suburbs
We missed the shore excursion we booked, but just hung around the cafes and shops near the beach.
It has a great vibe with good bars and cafes, plus some sailing/kayaking etc on the beach
We did a hop on hop off bus tour which was actually great. It takes you out into the suburbs which are really beautiful
Also I would have done the sailing cruise which comes included in the Maritime Museum ticket if I'd known about it. It's only ~NZ$30.