REI has the Lookout Pack (09 closeout) on sale today, at $54.98 + 22% off Coupon.  I have this backpack in gray, and it is durable, water resistant, and madly comfortable.  It doesn't include a water reservoir, but I purchased a Nalgene brand water reservoir from EMS after I bought this pack, and was pleased to find that if fit the pack perfectly (the bag has hose outlet for a water reservoir). 


This bag holds a ton of stuff (2 Days worth of clothes and some extra's) or a lot of items for a long day-hike.  Nice organizer panel on the front, plus nice slim, and large pockets.  Pretty much waterproof zippers.  The back panel is very stiff, and perfectly contoured to my back.  I find that the straps are incredibly comfortable too.  Lastly, I've been able to balance loads incredibly well in this pack, as I hiked some intermediate trails with rock-slides in the Niagara Gorge last year.  Checkout the bag at REI.com while there's still some left.  Use this coupon code today " OUT2DAY2 ", otherwise,  remember to look for others before you purchase it at another time.  A great way to get REI coupons is to subscribe to their newsletter, there's lots of offers in there.