Roadtrip from Phoenix to Yellowstone

We only have 9 days for our roadtrip from Phoenix, AZ to Yellowstone. We're leaving July 18 and have to be back by the 26th. This is our first ever roadtrip and we have 3 kids ages 13, 11 and 3 and we're taking our Sienna minivan (that means we need to stop in hotels to sleep). We were fortunate enough to get a cabin for 2 nights, the 21st and the 22nd, located at the Lamar Valley with the cabin 1 mile away from the northeast entrance of Yellowstone. That means we have the 18th thru the 20th to hit some POI's on the way up, and then the 23rd thru the 26th on the way back to Phoenix. The most north we've driven to is the Grand Canyon. We badly need suggestions on good stops and good eats. Thanks