I agree with Dave that you can fit everything you want to see into your travel plans, but I also feel that there is a point of diminishing returns where just adding more 'must see' destinations means that you won't see enough of all of those destinations to make each stop worthwhile. This is most obvious on Days Six and Ten when you plan to visit some fairly important, scenic and time-consuming sites on days which involve significant driving.

Remember that any driving time estimates you get from mapping routines assume constant travel at the speed limit. Those estimates make no allowances for food, fuel, traffic, sight-seeing...not even an occasional stop-light/sign. Your chances of seeing all three of Desert View Drive, Horseshoe Bend and Bryce Canyon while driving from the Grand Canyon to St. George are pretty much non-existent, or would at the very least defeat the purpose of taking a couple of weeks to tour the Southwest. As a RoadTripper who has learned the value of actually taking some time to experience the places I've spent so much time and energy getting to, I would encourage you all to try to do a bit less and enjoy it all a bit more.

In the end, you know your travel styles and stamina better than we do, but I would encourage you to think about two or three things you might be willing to drop at this point rather than asking for more things to see and do, especially on your two longest driving days. But we're always here to work out just such details.

One thing I would agree with you on is that May is probably better than September for this sort of trip. Summer vacations would not have started in earnest yet and temperatures will be, in my opinion, more enjoyable in Spring than late Summer.

AZBuck