Are you retired? Traveling that distance for a couple days at the Grand Canyon is a long, expensive trip. I'd recommend planning for a month or two to visit the whole immediate area as long as you're there.
If you can add more time at least spend time in the southern Utah national parks - Zion, Bryce, Capitol Reef Arches, Canyonlands in addition to the Grand Canyon. You could also easily work in Monument Valley which isn't a national park but very pretty.
If you're 62+ you can purchase the national Senior Pass which will admit you to these wonderful parks free and give you 1/2 price on campsites. It can be used in national parks, national forests, national wildlife refuges and other public areas.