It is the golden age of packs. If you can't find a pack for any purpose conceivable, you're just not looking. A good place to start looking is with Gregory. The California-based company only does packs, and as you might imagine they have dialed in the technology.
The Gregory Z series of hiking packs are perennial favorites here at GearFlogger. The streamlined 35 liter Z35-R weighs in at 3lb 12oz for a medium. It features JetStream LTS suspension, with minimal contact between pack and body for better airflow, but still plenty comfy to carry with a stout load. The space between back and pack is handy for stuffing a climbing rope or clothing layer that you're taking on and off as you move. The suspension is fully adjustable everywhere you look, and you won't have a problem getting the fit fully wired for your frame.
The R in Z35-R is for rolltop. The pack does away with the top pocket in favor of a simple rolltop closure that's fast, simple and leaves total freedom for neck swivel. There's a small flat pocket on the front of the rolltop, a large stuff-it pocket perfect for layers, and a medium capacity vertically zipped front pocket for stuff you want to keep out of the way. Inside is a hydration sleeve with clip and twin tube ports, and on the dual-adjustable waist belt are two small mesh pockets sized for compact cameras and snacks.
Although the Z35-R is billed as a hiking pack, it has technical features too: dual ice axe loops and ski carry loops on the side. Compression straps on the top and sides will let you attach additional gear as needed, so you can really go total yard sale if you feel the need. So the Z35-R is fast, light, comfortable and flexible. What's not to like? Only one small thing: no side pockets for water bottles, so you'll need to pimp your ride with some aftermarket bottle holders.