I agree. Personally I love [coconut] water. It's great for hangovers too!
I concur about coconut juice. When I suffered from severe dehydration, it was the only thing that got me back. Now I use it preventatively before, during, or after intense exercise. It is even used in IV's for severe dehydration because it has the perfect balance of electrolytes. It tastes good and none of the fructose etc. of sports drinks. there are several brands you can buy at stores such as Henry's, Jimbo's, Whole foods etc.
In response to Marea, who asks about a sports energy drink for her son... I have this suggestion. Coconut water. This is a natural, highly nutritive substance which I feel will meet your son's needs quite nicely. It is, quite possibly, the perfect after sports beverage. It is easy to come by providing you can secure a coconut, hammer, and screwdriver. Enjoy.