Regarding electrolytes, the best stuff I've found is DripDrop. It's pricey at $10 per box of 10 packets, but it's the most concentrated, complete and the best value per unit of electrolytes. It has a very slight citrus flavor, not excessively flavored or sweet -- suits me because I dislike the flavor of most sports drinks. Comes in little Mylar pouches, not much larger in diameter than a large drinking straw for milkshakes. Keeps each individual serving dry even in a sweaty pocket or rain. I tuck 'em into little niches in my saddle bag too.
When I can't find DripDrop locally (it can be ordered online) I'll grab some Propel in the same size packets, or Emergen-C in larger Mylar packets. But Propel is sweetened more than I like. Neither is as concentrated as DripDrop but Propel is really cheap, just a couple of bucks a box of 10 packets, and available at many places that also stock Gatorade (same company).
I've also used NUUN tablets but I don't carry the whole plastic tube, and even in a ziplock baggie they tend to absorb moisture quickly.
I've been prone to hypoglycemia bonks all my life so I also carry glucose tablets for emergencies. Cheap, works more quickly than gel packs, just chew one or two and drink some water. The diabetic supply section of any pharmacy is the cheapest source. Sporting goods stores also carry 'em, with a fancier label and higher price tag. I usually don't need them if I've eaten and rested properly, but stress is also a factor in bonks that's harder to control.