We get tons of free Power bar things because we're sponsored through TNT. We have been using their performance drink (powdered), and now are switching to using their "recovery" drink which has a bit of protein and more sodium/carbs.

The Power Bar drink stuff is pretty good, not too sweet, and you can easily sub in gatorade when that's all that's available. On the 600k, the Power Bar recovery stuff in my camelback went down really easily and seemed to stop the beginnings of a gatorade stomach ache.