I've been to Phoenix a half dozen times, though only twice since I've been Yelping. And last year, my road trip from Denver to Las Vegas brought me through Arizona with stops in Flagstaff and the Grand Canyon.
Yes, the Grand Canyon is absolutely incredible. A World Wonder in fact and you should not miss it. Please understand that it's not exactly close to Phoenix. It's at least a 7 hour round trip and understand that the Highway Patrol will pull you over for going faster than the posted 80 miles an hour speed limit.
But there's more to the state than the Canyon. The Lowell Observatory in Flagstaff was where Pluto was discovered. The Pima Boneyard is where old aircraft go when they're not needed any more. Monument Valley, on the Arizona/Utah border. The Hoover Dam, on the Arizona/Nevada border. Sedona, Havasu Falls, Petrified Forest. Antelope Canyon. And I've only been to *some* of those places. Writing this list has me thinking that I need to be back in Arizona. Soon.