Yesterday I had a pre-ride snack of an English muffin with cheese, along with a yogurt smoothie. Today my pre-ride snack was an English muffin with peanut butter and a yogurt smoothie. And guess what - the peanut butter was vastly better than the cheese from an energy standpoint.
You're right - I've known that peanut butter is a wonderful energy food for a long time, but the direct comparison was definitely interesting. I only buy fresh-ground peanut butter, so there's nothing else there but peanuts. And peanut butter rocks!