We have an REI that just opened here, and finally took the opportunity to visit for a bit. I didn't get to check out all of the packs I was interested in due to a grumpy 3 yr old.
First I tried the Kelty Coyote 80, and thought it was good. We have a Kelty child carrier and I have been pleased with it.
But then I tried the Dueter ACT Lite. It seemed much better built. It felt like a pack that would last through many tough and crazy adventures and still be around when I'm gone! I certainly like a sleeping bag compartment. I think I may have found a winner. I'll keep looking though.
We decided to get a membership since we have several expensive items to upgrade, and spending $10 a year would be simple even when you don't need anything.