Definitely things with salt if it's going to be warm out…pretzels etc. At D2R2 there were pickles/pickle juice at some of the rest stops and those were quite popular. Bananas, orange slices, etc. are always good. I've found that sweet stuff becomes somewhat less appealing the longer I ride…for example, Oreos are normally my big junk-food weakness but I recall one ride where they were available at a rest stop and I think I stopped at one, because it just wasn't what my body wanted at that point.