What would you like more suggestions for -- additional stops?
If you're going to the North Rim, then Bryce, Zion, & Grand Staircase/Escalante are in your way also as you head to Las Vegas. I'd visit as many of those as you think you can fit in. At the same time, each one of these is an easy day trip (or weekend) from Las Vegas, so if you're pressed for time at that point, you can always visit them later.
If you'd like to see some photos of the area I'm recommending you see, check out my recent photos of the Grand Staircase Escalante National Monument . There are 4 albums currently posted. One is for Grand Staircase/ Escalante specifically; also, the album titled "Utah SR12..." contains photos of the same area. The "Lee's Ferry" album is also on this route (on your way to the North Rim on US89A (near Marble Canyon, AZ and Page). Lee's Ferry is a historic site, location of the only practical crossing of the Colorado River for 600 miles. The river there is now crossed by a steel arch bridge.
Bob