I generally take one or two bottles of accelerade. sometimes one accelerade and one gatorade. i like the taste of powerade better personally, but it is hard to find around here.
I've done best stocking up on breads (bagel usually) with water as a backup. On long rides, I do the unthinkable and load up a camelbak full of accelerade, one bottle of plain water, and two pockets full of bagel. not being much of a fruit person.
but definitely test out what works best over your endurance rides. i test saddle comfort, shorts, food, hydration, etc. i notice that it sometimes shifts around, so what worked one time doesn't really work several weeks later. the key thing is not to suddenly try something new the day of a long ride.