Looks like a pretty good itinerary. Not too rushed. I haven't been to Dunedin or Oomaru, but i've done the others multiple times.

My only suggestion is that neither Holiday Inn option in Queenstown is in a good location. If I had to pick one, I'd pick the Frankton. But you're driving to get anywhere with either. They aren't really 'in' Queenstown at all.

If IHG is a must, see if you can book the Crowne Plaza Queenstown. Otherwise, I'd suggest just paying for a hotel there. It's a nice place to walk around, but it is touristy, there's traffic, and parking can be annoying. It might look like a 5-10 minute scenic drive but it will end up being a 20 minute ordeal to get there and parked. It's not something you want to deal with on your holiday IMO.