I would suggest you do this extension. YES it is expensive and it is a long time on a bus but to miss Queenstown is to miss the best of New Zealand.
Finding a local operator is probably not that the best option in this situation. It is along way in a bus and quite a distance from Milford into Queenstown. If your local guide does not show up in Milford you are doomed. There is absolutely nothing there but the old Milford Hotel. I think a private situation could end up being more expensive in this scenario and would advise against this option. This is not Asia and locals are expensive particularly for something like this.
SHOTOVER JET BOAT Any free time you have the hotel you are staying at will set up the shotover jet excursion. They run constantly, pick you up at your hotel or a meeting place in town and bring you back. Easy to do this on your own. Any jet boat excursions will be fun so it is not necessary to do this in Queenstown.
ARROWTOWN I did not remember them including Arrowtown before, they may have I just did not remember that. It is a quaint place and I think you will enjoy that.
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