Ok so I went to the store and tried all of these on, but I am still unsure which of them to choose; if any.
Kelty Tornado 4200
I think this pack may be too big. My trip is less than two months long, but I am also looking at my pack as an investment for future (hopefully longer) trips as well.
I also liked the side pannel acess in addition to the top loading feature.
Kelty Storm 3600
The size of this one seemed to be more appropriate. I also like that on both the Kelty packs there is an expandable pocket in the front that I can shove my empty daypack in (since none of the packs I looked at had detatchable ones).
Lafuma Hunza 50
This pack was the most comfortable (but that may have only been because of the way the straps were adjusted) and I liked the size and the fact that it had a rain cover.
So have any of you nice folks ever used one of these or have any general suggestions?