I've tried all the gels it seems. Running is particularly hard on my digestive system - but Accelerade gels are the easiest (a thinner consistency than others, so it feels you can drink it). It is also the only one recommended for activity over three hours. Others are designed for a quick burst for an hour's workout or two. Accelerade is also gentler on my stomach and it claims it is good for those that are hypoglycemic.

As for your electrolyte loss, try supplementing with tabs in addition to your gels.