I don't know about Gels, I think those are more for the racer crowd where they need to make sure that the length of a stop is .1 seconds or less. They can be expensive and most taste like crap. Taste is a personal preference, so you need to try different ones. Sometimes dollar stores and variety stores will have them, but like anything else in those kinds of places, check expiry and best before dates.

I find a bag of Gorp,works wonders. Gorp means Good Old Raisins and Peanuts, although any nut or variety of nuts will do, toss in a few Smarties, and some shredded coconut your good to go. When you want or need to eat, find a nice park bench, sit down, have some gorp, and some water, rest a couple of minutes, then get back on and go...... I like the bulk food store for this, as you can get different stuff in smaller amounts......