A better plan, with a few suggestions:
- Some of the better thermal parks are between Rotorua and Taupo. So, get to Rotorua, perhaps stay there, then head to taupo, and on the way see Wai-o-tapu. Also the redwood forest near Rotorua is lovely. I personally didn't find much worth seeing in Taupo.
- Greymouth is a very boring town, and I wouldn't go there just to see glow worms. However, it's also one of the few places to stop between Picton and the glaciers, so there is a case for using it just to stop, but, if possible, go straight through to the glaciers, Greymouth, and its glow worms, are NOT worth it on this trip.
- If you pay, a lot, you can see Franz Josef Glacier on a tour, by being dropped on to the glacier by helicopter. Choose which ever glacier has the best tour for you - they are close so it's not hard to go between the two.
- I disagree with #5 about Queenstown. It's a fabulous place. Great views and heaps to do. Go to Arrowtown, go up the gondola and admire the views and ride the luge, visit wineries, cruise on the lake, take a jet boat tour at either Shotover or one of the other locations, drive out to Glenorchy. It's well worth a few days. We loved it so much we're going back there soon. However, on a 9 day tour I agree it's not worth 3 days
- The Te Anau/Milford bit is still a mess. There are NO jet boat tours of Milford (or at least none I can find). There are tours that combine a jetboat ride in Queenstown or elsewhere with a trip to Milford, but these are 2 separate things (at least as far as I can find) you get there one of two ways - a five hour drive each way (so, a 12 hour day trip) or, you fly in, get on a boat, and fly or drive out. Te Anau has a fabulous glow worm trip, which is well worth seeing on a stop over. However, again, I disagree with #5. WE though Te Anau lake was pleasant, but not spectacular.
So, on the last bit I'd suggest the following:
- If you can afford it, take a trip that flies into or out of Milford, take a cruise on the sound, then take the bus back. The hour or 2 of the drive close to Milford is every bit as good as the Sound itself, but this will involve you in a 5 hour drive back to Queenstown.
- Or, drive both ways, either as a tour or with a hire car, and stop overnight one way in Te Anau to break up the journey (Id' stop on the way there). And the do an evening glow worm tour. It stays light til very late so you have plenty of time to see the lake should you wish, but the glow worm tour starts with a lake cruise to the caves in any case.
With your additional day maybe spend time in Wellington, or in Picton spend another day seeing the Marlborough wineries or a day walk on the Queen Charlotte, or on the way to the glaciers divert via Nelson and Abel Tasman, or on the way from the glaciers to Queenstown stop off in Wanaka.
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