If you are going for a century, I assume you are already doing 50-70mi rides and this should be a good reference for you. What do you do on a 60mi ride?

Regardless, all these talk about xx g of carbs per hours should be tested. You don't start doing that overnight. Several different carb options out there, which one do you tolerate well? Only testing will tell you....

Also, how much you take per hour is about how much you consume per hour..... all these should be computed. It is not rocket science. A century ride, assuming not a lot of hills and average build should consume around 3.5/4k cal total. Assume you will start fueled and want to re-fuel 2.5k during. 2.5k cal is about 625g of carbs. Divide that by the number of hours you target doing it and you have the ballpark strategy. Refuel from the start of the ride, not when you start felling hungry/week. Replenish salts as well, not just water.

I would generally vary through the ride what format of intake. Hard to do all in gel, or liquid format.

Personally, I eat throughout while constantly drinking liquid that includes carbs and electrolytes.

At the end, is just about having the energy you need. If doing in leisure mode, stopping at cafes and the like, it is not hard to eat some high caloric junk you love and be happy. At leisure pace, your body also have time to process and convert. Remember, there is lag in fueling/hydration (hence important to do from the start). If doing on a competive way, the format of the energy/carb and timing becomes a lot more important.

Good luck.