If you already had a bladder I'd suggest one of the Wingnut packs, they are light, pretty waterproof and have a lot of space, but they aren't cheap, especially if you have to get a bladder as well.
I've got the enduro pack, which is a little bigger than a hawg, but is far far more comfortable than the mule I have, even when I have a lot more stuff in it. It is really handy being able to get at sweets/tools etc in the side pockets without taking the pack off.
Camelbacks have the best bladders, imo, and are really well put together (so is the wingnut), so they are always a good option, I wouldn't go back though.