05-11-2016, 07:10 AM
I've been across the southern routes a few times (40, 20, 10). I'm envious of you. No matter what route you end up taking, you're gonna have an amazing experience!
check this site out for "world's largest ball of twine" type stops. Super fun to stop and grab a picture to break up long hours on the road.
for desert and cactuses, the big saguaros, 8 to 10 will take you through the Sonoran desert and saguaro country. You'll think you're in the Sahara, then the old west.
For views, the drive from Flagstaff down to Sedona is priceless. Sedona itself is worth a stopover - looks like the surface of Mars.