In reply to mantlej:
it seems like every old-school climber in NZ carried a Macpac Ascent. it's the standard down there for sure. I don't know your experience level, but I would not recommend getting anything over 60L - especially if you are staying in huts. Kiwis seem to carry all sorts of crazy shit into the hills (like loaves of bread in hard cases). I can say for certain that climbing with a 75L pack is pretty stupid. I've tried it and it's a pain in the ass. my standard pack for all my multi-day climbing is about 50L. For a climb like the NW or SW ridge of Aspiring, I can't possibly imagine what you'd fill a 75 L pack with. If you had plans for something that required a multi-day walk in and then a multiday walk out, maybe 75L would be needed.
It doesn't really matter what brand of pack you get (as long as it's a high quality one) - make a list of the features you want - and then go look for a pack that closest matches your ideals. Macpac is pretty burly and old school - I'd look at the 60L offerings from lowe alpine, osprey, black diamond, the north face, gregory, deuter, podsac, etc... I know many people don't like the current made-in-china Macpac offerings.
If you need help picking features that you want - Marc Twight's Extreme Alpinism has a good list.
You're going to end up needing lots of packs if you want to do lots of different types of climbing. But it's hard to go wrong with something in the 60L range - it's big enough to support multi-day endevours, yet small enough that it's practical to actually climb with.
hope that helps.