As Ive read this thread, I've hesitated to post to it for no other reason than it seems you all drink quite a bit more water than I do during a ride, and I live in the desert. I'm wondering if it's because working outside here I make sure to start out hydrated to be hydrated. If you're not starting out hydrated, you'll never catch up during the ride (or working).
I carry one 25oz insulated water bottle with me which will keep me fine for 20 plus miles on all but the hottest days, and I make sure I have refill spots along the way. One thing I do is I hydrate well the night before. I drink more the night before than I do during the ride, and water up again before I leave.
The only mix I use during the ride is a powdered sugar free energy drink that I mix up if I start to run down a bit. If I need electrolytes, I'll get a Powerade Zero after the ride.