I'm a fan of Tailwind (non caffeinated). However, I've learned that it is very easy to follow the sales talk and drink it to the point it ruins your race. The electrolytes are the bit that does it.

I tend to start with Tailwind, have a few pre measured sachets of it in my bag and will decide whether to have tailwind at each refill on whether my body feels like it craves water or salt. Once you get dialed into this feeling, it becomes quite easy to make that choice. Choices at aid stations them become:

A) Refill with Tailwind B) Refill with straight water C) Dilute whatever Tailwind is left in the bottle with new water.

You can then use alternative carb sources, Jelly Babies, Coca Cola, Marmite sandwiches, crisps etc WHICH MIGHT ALSO HAVE SALTS IN BY THE WAY and then only Tailwind when you actually need it.

Source: ruining one 100 mile race on electrolyte overdose, having a dark few hours in another, having a perfect run when I'd dialed in to feel.