+1 on the pedialyte (get the generic, CHEAP!), but I can't get any kids to down that stuff unless they're really young (infants seem not to mind)

I prefer not to drink electrolyte-rich fluids exclusively...yuck! But there are times when on a huge hike I can tell I'm "sweat out" and need some salt...I just grab some trail mix and throw down a couple bites. Presto! Salts are back.