I used to have the jepp aviator. It was always awkward to carry around with just the handle, I'd lost the shoulder strap a while ago.
Just recently bought a Military style CamelBak.
CamelBak Products LLC
It serves well with holding all my charts and overnight gear.
Probably the best thing about it is having the pack sitting directly behind me with the hydration tube coming up the left side of the seat.
%90 of my flying is fairly remote so need a lot of water handy. And the tube makes drinking a lot easier rather than having to juggle an open bottle in turbulence.