Like DrIsotope alluded to, try Powerbars for one long ride. After that Clif bars are like a Michelin 2-star appetizer.

In most areas, I've defaulted to getting off the bike and walking into a convenience store every couple hours. Fill up the water bottles and live off the land, so to speak. Oreos or Fig Newtons are great, a Honey Bun has enough carbs to go another two or three hours. My favorite is the fried cherry pies, if they don't have the el cheapo brand with hardly any cherries inside.

I even had a frozen burrito once. In my defense, Crowheart, WY doesn't have much else. Three Clif bars, if I'd had that many, would have got me up the hill to a "real" town.