Was thinking of doing this as well, though I don't usually drink coffee. If we're thinking of the same thing you're talking about the frappucinos and the only difference between them is flavors (obviously up to you). Edit: actually I think they have these things called "double shots" which obviously by the name provide more caffeine. I don't know if you'd be into that.
Others have recommended not to eat too heavy with the argument that their brain works better in a slightly starved state. One can immediately see the evolutionary justification, but I have no idea if it really is a universal thing. However, I've found this to more or less be the case for myself.
I think a good rule of thumb would be to bring whatever makes you feel most comfortable that simultaneously isn't too filling. I'd start out eating a complex carb (bagel, oats, toast, cereal, etc.) in the beginning and use glucose in the home stretch (fruit/chocolate), with protein throughout (hard-boiled eggs, light amount of pb, tuna n' crackers, bars...sushi would be f*cking awesome if you can get it).
