Hi susanmerry, welcome to the forum!

NZ is difficult to see without at least some driving/sitting on a bus. Attractions are well spread out and it takes much longer to get from one place to another than you might expect. Not every town has an airport, many places have one way engress (such as Milford). To get to Milford, you must drive/take a bus from Queentown (four hours each way) or Te Anau (two hours each way) OR splash out for a coach and fly combination like this:

http://www.everythingqueenstown.com/category/milford-sound-and-fiordland-national-park/milford-sound-coach-cruise-fly/

Plenty of companies offer wine tours in NZ. Just search by area - for instance Marlborough, Nelson, Central Otago, etc...we once took a wine tour in Blenheim and it was only us and another couple, excellent. I suggest you look for operators that cater to small groups as you'll have more flexibility, meaning the tour operator may let you pick the wineries. Small operators tend to visit boutique wineries, whereas big operators (such as those based in Queenstown) tend to stick to the big producers. I know which I'd choose.

Some info in wine tours here:

http://www.tourism.net.nz/tours/wine-tours/index.html

Busses CAN indeed be be backpackerish...I met a young woman on the SI last month who was very disappointed in the Stray Bus as it catered to young people wanting to party more than those wanting to see the country. If you do decide to take a tour, I'd suggest you look into those that cater for the over 50's.

http://www.relaxingjourneys.co.nz/escorted_tours/index.php

For airport shuttles and transport to/from locations, you might take a look here:

https://www.supershuttle.co.nz/Default.aspx

http://www.atomictravel.co.nz/

http://www.westcoastshuttle.co.nz/

You might also consider incorporating a train or two, although the train service in NZ is very limited:

http://www.railnewzealand.com/

I hope this helps get you started.

Oops, meant egress.

Oh my goodness, thank you! Very, very helpfull.
I had begun to figure out that things are more spread out than they might appear, so your links/suggestions are a big help. As I mentioned, I found a country-wide bus pass with unlimited travel (the backpakerish one), but now am thinking it might be better for me to buy one for my daughter to use after I leave. She'll have months to tramp about.
Not sure about tours for "over 50's" - sounds terrifying! - but I will certainly look into it. I really like the sound of your experience with a small operator, though, sounds exactly up my alley.
I am starting to think about a train to Wellington (have a friend near there with an olive grove), then (bus?)to Marlborough for wine, then fly to Queenstown. I would like to get to Dunedin as well, but this may be unrealistic with only 3 weeks.
Many, many thanks for your suggestions. You've steered me in the right direction.
Best,
Susan (from Canada)

You can either fly or take the ferry from Wellington. The ferry takes about three hours and ends in Picton, from which it's only about a 25 minute drive to Blenheim...Marlborough wine country.

Much to my surprise, the www.relaxingjourneys.co.nz is turning out to be a great resource! Really, they are just taking out the pain of making my own arrangements, everything is customisable. I am working on my itinerary, where I want to go, how long I want to stay in each plpace, and they are making all the arrangements. No tours, icky "groups", nothing to be afraid of. So, thank you for the suggestion. I am putting together a wonderful trip of my own design, planes, trains and coaches and the price is VERY reasonable.
Many, many thanks for the suggestion.