My new favorite way to hydrate is by eating Cliff Shot Blocks at a rate of about one per 15-30 minutes of hiking and down it with water. This way no mixes foul up my water bladder. They taste good and some have caffeine. They're chewy, sort of like jello but more firm. They don't seem to melt at under 100F or so, and you can eat them one at a time without touching them with your hands by squeezing them out of the package. I have noticed a real difference in my energy for hiking while eating them. I also didn't seem to need as much "real" food as I was both hydrated and had consumed a few hundred extra calories along the way.

So far I've tried lemon-lime, orange, cola (caffeinated) and strawberry and liked them all.

And to stay on topic, I drink around 1 liter for every 4 miles or so unless I'm sweating a lot.