Some sort of fried potato and, as a nod to Eugene, readily available at truck stops (plus fast food joints, gourmet food places, etc..). Try not to get too crazy with the road food to keep "intestinal" issues at a minimum.
Also avoid dehydration with water and maybe some electrolyte solution. This past May, I drank some beer meeting some BPLer's (including Eugene) near Santa Fe, then inadvertently doubled my usual coffee in the AM. Slept very sound at the TH but, in retrospect, I should have forced some water though, as I became very dehydrated on the trail.