John, sounds like you are using your trip to NZ as an excuse to buy a new lens!
I think 17mm on the 17-55 is wide enough and the results will be surprisingly good. It took me a long time to accept that this free lens was near as good as the 24-85 I paid $800 for but it is! When we took a chopper ride to the top of the Franz Josef glacier and I only had room for one lens, I took the 17-55 which proved the right choice (but was psychologically hard to make), I showed a pro photographer one of my glacier shots and he simply could not believe it was taken with a D40 with the kit lens!
These following comments refer to FX format as they relate to film cameras. When I bought my 24-85 I really wanted the 24-120 VR but could not afford it at the time. After having a 70-200 for previous camera for years, I had come to the conclusion that an ideal zoom for my style of photography would have been around 35-135 and the 24-120 was perfect for me (and I still don't own one!) Since then, I am pretty sure Nikon have added an upgrade to the 24-120 so today the argument is even more compelling. The 85 mm limit was always a limitation on film and I thought I'd eventually get a 70-300 to round out my collection. Your 17-55 in the DX equivalent of this lens so I understand your frustrations!
If it is your intention to eventually move to FX and I was in your position (eg just with the kit lens and no legacy ones), I would find the extra $150 and get the 24-120 in preference to the 28-300.
If on the other hand, you thought the D7000 was more than enough of a camera for you and you are quite happy to stay with the DX format then there is no compelling reason to spend the extra money on FX compatible lenses. If that is your direction, I think then you need to make a choice as to which way you wish to grow your lens collection. Is it the long end or the wide end that you should buy first?
At the long end, maybe consider the 18-200 VR or the FX format 70-300. From what I've read, the 28-300 is short on full zoom so it will only give you about 270mm so you won't loose that much with a 200 mm maximum limit and I think you will get better IQ.
At the shorter end, the consensus here is the 10-24 is the way to go and it would fit well with the 18-200. I would not just buy something for you NZ trip but think about what frustrates you now and choose which end you want to buy now. In NZ, you'd probably get quite a bit of use out of your 10-24 but you are going to use your kit lens as your walkabout lens and the 55mm limit will be frustrating. I think therefore, you'd be better off going with the long end first and get the 18-200 (the cheaper DX equivalent of the FX 28-300) and pocket the $350 you save and put it towards the next lens purchase (or buy a 35mm F1.8 with the change so you have one low light lens).
Sorry for being long winded. In my case, I started digital photography with a DX camera and quite a decent FX lens. I have built my collection around the FX format and this means that I am forced to follow through with buying an FX format body hence the D800 is on order. I deliberated a long time on which way to go and considered getting a D7000 in which case my lens collection would have ended up looking totally different to what I have now (which are listed in my profile).