Up until a couple of years ago I was using a Camp Trails external frame I bought in 1990. I have no major complaints with it other than the weight which is well over 6 lbs.

Now that I 'm older, I'm looking for a lighter pack and most of those are internal frames. One of the packs I'm considering is the Osprey Exos which is one mentioned by Glenn. REI has a pretty good selection and I know they used to rent gear but not sure if they still do.

I think though that my preference would be to try some on with weights and see what works for you and buy it if it's not too far beyond your budget (the Exos at REI is $220). That way you'll have something that you like and fits you properly as opposed to a limited selection at a rental place.