Just a very recent update on the Auckland situation. I've stay in both the Hilton and the Westin this month. In both hotels I booked the cheapest room with king-size bed available on the internet. And this is what I got:

Hilton
As a Diamond VIP I got a free upgrade to the Bow Suite - which was slightly impaired by the renovation work. But nothing major, just bathroom windows were covered by a permanent blind. Still, the Bow Suite and especially its balcony are fantastic. I also got a free continental breakfast buffet in White's, but would have had to pay an additional NZD 10 for the full buffet. I didn't get any other amenities, such as a fruit platter to the room. Bottom line: I got exactly what I'm entitled to as a Diamond VIP, but nothing more.

Westin
As (lowly) SPG Gold I got a free upgrade to the Deluxe Room, which is about the size of the Bow Suite, but only with a very small balcony. The room, like the entire hotel, looked newer, fresher. Obviously, I was charged NZD 25 for the continental breakfast (nobody ever promised free breakfast for SPG Gold), but I was given the promised late check-out.

Bottom line: Both stays were absolutely fine and I got everything I was entitled to. I'd rate the Westin slightly higher, unless you really have a lot of spare time to enjoy the Bow Suite balcony. However, given the proximity of the findings, price is a valid argument for both - neither one is really worth a much higher price.