My take on hydration,
I take apple juice, and cut it 59/50 with water. The problem oath sports drinks is the sugars, chemicals, and the electrolytes. While the electrolytes are good, but too much of them and they throw off your own personal electrolytes, as it were, causing in certain cases an electrolyte imbalance.
I worked in many hot conditions, and the apple juice/H2O did the trick. Also keep a close eye on the color of your urine, it will tell your hydration story.
Here's a few charts,
