For a trip of several days you would need a pack with a least 4000 cu in, quite likely even more, unless you are going ultralite. Quite a few manufacturers off suitable packs in this range. I would definitely stay away from external framed packs. Internal frame packs are available which can fit well and carry easily. They also stow better in boats, planes, etc. Fit is all important, so it is a good idea to buy from a good store, or follow the fitting instructions carefully if you buy mail order.<br><br>Neither JanSport or Eagle Creek would be my first choice. I am not aware that Eagle Creek makes anything in this size range. They seemto do a competent job on smaller items. Based on their products back in their early days, I think of Jan Sport as producing second rate equipment. I am not sure if this is true today, but why take a chance.<br><br>Good equipment manufacturers for your backpack include Gregory, Dana, Mountainsmith, Arc'teryx, and Kelty. Many of these are owned by larger firms; I am not aware of any pro- conservation policies on their part.<br><br>In that regard, I would suggest REI, which seels the brands I hve mentioned above and also supplies a very decent line of house branded packs which you might consider (they are a verygood dollar value). REI does divert a portion of their profits into conservation efforts, although they have emphasized such activities in their recent literature. None of the companies is as consistently environmental in thier policies as Patagonia, the gold metal winner in this category. Unfortunately, they do not make a pack in the size range you need (great smaller stuff though).<br><br>Backpacker magazine does fairly decent product reports which have been objective and reliable enough in my experience. Consumers Reports has never rated the larger backpacks, although they have done smaller backpacks in the past.<br><br>Fit is everything. I would advocate buying in a store, and load up the pack with a realistic load to see how it carries, paying particular attention to the feel of the pack as you make awkward off balance moves as if you were climbing or bushwacking. Even people who intend to stick to trails sooner or later have to crunch brush.<br><br>I now use a Mountainsmith model which is eleven years old. Bought with care and not abused, though well used, it still serves me well. On the job I recently carried a smaller Arc'teryx model which impressed me with its quality, comfort, and durability. I would carefully at their models, as well as Dana which has a very good reputation. <br><br>A pack of this type is a major, significant purchase. I would make sure to get a model that meets my needs (and my body), that is comfortable and that works well in off trail situations. I would then pay whatever it costs. Money won't count when you are deep in the boondocks, humping your gear around.