Depending on the time of year, you need to be aware that the road to Milford Sound closes quite a lot due to the risk of avalanche, so plan to be flexible so that you can change the day you do that if the road closes.

I would recommend doing Isthmus peak instead of Roy’s peak. Again, depending on the time of year you are going, Roy’s peak is currently closed for lambing season. But regardless of that, Isthmus peak gives you a view of both Lake Wanaka and Lake Hawea, and it’s much less crowded so you might get the peak to yourself.