There is also a book-I think it is still in print-Next Exit the problem with the book is you have to stop or have a co-pilot get it out and read it. I have had one for years and generally do not use it.
Mostly I use Gas Buddy to plan where I will find low cost fuel and Google Maps to zoom down to the street level to look at the stations access. Google also lets me see food places around the planned fuel stop. You can find RV parks, stores, and just about any service you need on Google Maps.
I have also found Google to be pretty accurate about driving time, and I just need to add my estimate of how long we will spend eating, fueling, etc. to figure when we will arrive somewhere.