We stopped at Franz Josef on our way from Picton to Wanaka.
Just fyi for people who don't know, Franz Josef is a glacier.
You can choose to walk a marked path to the bottom of the glacier or you can choose to charter a flight onto the actual glacier. For travellers thinking of booking a helicopter tour, make sure you leave ample time in case of bad weather! We were lucky we didn't charter a flight as the weather grounded all flights on the day we had set aside for Franz Josef.
Walking the trail to the bottom of Franz can be done in any weather, provided you bring the right clothing and gear. If you do attempt this trail in the rain, you definitely need to have a rain cover for your gear. There is no shelter and your equipment will be drenched. We lost one of our DSLR's to the rain.
It is a fairly easy walk with plenty of markers and most of the walk is fairly flat. Depending on the time of year you decide to visit Franz Josef, be prepared to be disappointed. From the pictures we had been shown at information centres, the glacier extended right down to the valley. We went to Franz in mid-April and the glacier had retreated nearly all the way up the mountain.