I always fuel up before a ride with some carbs and protein. When it's not blazing hot I sometimes don't need anything else for several hours, but in warm weather or if the route is hilly, it usually goes something like this:
2-hour rides get a couple of Clif Bloks
2 to 3-hour rides add a bar of some kind and a Nuun in water
Over 3 hours add a PBJ
All rides get a beer afterwards or during. Sometimes a taco.