Every national park has a web site like this. Do all the 'clickies' and you'll learn a lot about the parks - what to do, where to stay, road information, special alerts.
I'd highly recommend that for every national park you stay in the park itself for the best overall experience. If you're driving all that way to make the national park your destination, why would you want to stay somewhere else?
Grand Canyon has two beautiful dry campgrounds (no hookups) and one RV park called Trailer Village. They are just steps away from the canyon.
https://www.nps.gov/grca/planyourvisit/camping.htm