When doing long training runs and races (half marathon through marathon--ultras are a whole other thing entirely!!), my preferred energy source has always been gels, rather than drinks like Gatorade. (Mostly Gu, but I did get into Hammergel for a while.)
I recently received a few samples of this new energy
gel from Justine at Ignite Naturals.
Called Reload, it's made from 99%
organic ingredients. The base ingredient is organic fig paste and,
according to the literature I received
along with the samples, is easily digestible and, as a natural form of
sugar "contains quality minerals that enhance the delivery of glucose
nutrients and oxygen to working muscles." You might want to keep it in
mind for your upcoming long training runs and races!