Yep, I use gels too and they seem to work, although I have to say I have never tried a long run without taking them. I use Gu gels (www.gusports.com) which taste great, but have to be ordered from the US. Postage costs add up but gels are $1 compared to £1 in the UK.
Gels and sports drinks serve slightly different purposes - Both are usually designed to give you carbohydrate, which your body needs as a catalyst to burn fat. The sports drinks will be better at hydrating you. Depending on which gels you go for, some you need to take with water, some you can take without and are self hydrating.