I'm personally a big fan of ultra-wide shots - as you can tell! - and also find a telephoto invaluable. But if you're not careful it's easy to find yourself with a gap in a twin lens system. For example, Canon folk might go for a 17-40mm and a 70-xxx, and find all the shots they want to take are between 40 and 70mm! At least there's a smaller gap between an xx-55mm and a 70-xxx though...
Telexstar, I just remembered you asked about recommend BBH hostels. You'll notice the BBH site allows people to rank them, giving an overall percentage. The trick is to avoid anything below 80% and aim higher if possible. See http://www.bbh.co.nz/listings.aspx#
Here are our favourites:
Auckland, Mount Eden: Bamber House.
Wellington: no decent BBH we've found, but a great YHA.
Christchurch: Dorset House
Dunedin: Hogwartz (yes, spelt that way!)
Queenstown: Butterfly Lodge
Nelson - lots of good choice - check the BBH guide
Picton: Sequoia Lodge
Marlborough Sounds / Queen Charlotte: Mahana Homestead Lodge
Wanaka: Wanaka Backpaka or Purple Cow