We choose cruises based on places we want to stop, and have preferred Celebrity when possible for the past 15+ years.
Things we liked:
Every place we stopped. Love New Zealand.
Sunset Veranda at back of ship, deck 8, right in the middle. Larger than average balcony. Bed closest to the balcony. Comfortable room, great service. No overhead shelter from the rain or sun but otherwise a great location. We like the aft cabins.
Rented a car and spent 2 days on the coast, then 2 days in Sydney. The zoo is overrated. Best to just ride the ferries!
Port is just average. We went to Coco Monde and had the best hot chocolate I've ever had. Something about Australia and hot chocolate--they know how to do it right.
Booked a private tour that included Mt Wellington, Bonorong, and Richmond. The ship didn't offer anything that included all 3. Loved interacting with the kangaroos.
rented a car and drove to Blenheim, then to Havelock and back to Picton. Great scenic drive. Watch out for great views of the ship coming into Picton!
rented a car and went first to the Polynesian Spa for the hot pools. quiet and uncrowded. Then went to Whakawewera for the village tour and cultural show.
wasn't impressed with the city that much. mostly passed some time before getting to the airport in the afternoon.