I went and climbed Roy's Peak in Wanaka. I really enjoyed it. The trail was a total return trip of 5:30 for me, and I felt I was going slow. The total distance was 16km, and an elevation gain of 1165m according to my gps. The weather forecast was suppose to be raining all day, but I got to the trail head around 09:30 and the rain stopped. As we climbed the weather steadily improved, opening up the view of lake Wanaka.
Part of the trail runs through private land where there are many sheep wondering about.
This trail is already pretty popular, so if you really want to enjoy it, come during the off season and be prepared for the changing alpine weather.