How much time do you have available for this trip? If you are heading to Zion, then Bryce and finally Capitol Reef I would suggest taking UT12 scenic highway and UT24 as suggested earlier. Unless you have time to consider visiting Arches and Canyonlands I would suggest continuing to Hanksville and then head South on US95 through Fry Canyon. It's a lovely drive that then gives you the option of going all the way to US191, or take a more challenging route down the Moki Dugway. (A search will show you what to expect, I found it to be a great experience and perfectly safe and that was in a 30ft RV.) If you had the time this would also give you an option to take a short detour to Goosenecks State park.

Buck mentioned Cameron on US89, the Cameron Trading post has dining, fuel and a cool shopping experience, and is worth a stop in my opinion. (It also has lodging available should it fit with your plans) There is fuel at the Hollow mountain gas station in Hanksville, the small store being built in a hole in the rock. Lodgings in Springdale are the most convenient for Zion with a free shuttle bus taking you into the park from town. Bryce canyon has lodgings near the entrance to the park and Capitol Reef has options, including a nice Best Western.

This thread is in Fall and Winter, if you are travelling more into the winter months be sure to pack warm layered clothing, Bryce in particular can get very cold due to elevation. If you wanted to break the journey home into 2 days there are limited options in Monument valley, or as mentioned earlier, Cameron Trading post and of course, Flagstaff.