This was our trip in June when I was burning SWA and Marriott GCs in order to keep our cash outlay for the vacation low. If we'd had a bigger budget, I would have stayed closer to the parks proper, but since we didn't, Courtyard St. George it was.

Day 1- Fly to LAS, drive to St. George, Utah
Day 2- Zion NP
Day 3- Zion NP
Day 4 Bryce Canyon NP
Day 5- Drive from St. George, UT to Flagstaff, AZ, stop at Pipe Springs NM, Vermillion Cliffs NM along the way, decide seeing the north rim of the Grand Canyon would have added too much driving time that day, even through we went right past the turnoff for it. Evening at Lowell Observatory in Flagstaff.
Day 6- South Rim, Grand Canyon, NP
Day 7- Flagstaff to Las Vegas, obligatory stop at Hoover Dam tourist trap
Day 8- somewhat early flight from LAS to home

All three of those parks had a good number of excellent photo options that required very little (quarter mile or less) walking and could even often be done from a car window. And yeah, if you're a serious photographer, you're probably going to want more than one day at Bryce.