Stayed at the Hilton Queenstown in March 2014. Booked a 1 bedroom with a balcony overlooking Lake Wakatipu. Keep in mind, this is what is known as the Frankton Arm of the lake, with Frankton being where the airport ZQN and a small, but well stocked shopping center are located. You are about a 10 minute drive from downtown Queenstown or about the same amount of time by water taxi. Never took the water taxi, but I wished I had tried it once. But you do have a nice water view, albeit at the end of a small section of a very large lake (go up to Gondola Peak and you'll see a fantastic view of most of the lake).

If you book a residence, which is very nice, even though you shouldn't be staying in the room much, being that it is Queenstown, make sure you don't get slightly downgraded to a studio. That's what happened to me because I arrived a day late due to extreme weather and a plane diversion. Flying from NRT to AKL, then connecting to ZQN, but the flight into AKL had an aborted landing (about 200 feet above the runway before the engines cycled up to full power) and was diverted to WLG. Missed my AKL-ZQN flight and my first night.

Breakfast was good. Being a Diamond, continental was free with a $10 upcharge, IIRC, to full cooked. Decent restaurants and bar in the complex if you want to stay in, but lots of good choices downtown.

Have no information about the Doubletree, which I would assume is in or closer to downtown.