Seeing the restrictions on Antelope Canyon, I'll probably cross that one off the list. I have no idea which day I'll be there and it's not like other spots haven't been added since my initial post. I'm only semi-retired so time is still an issue.
Ranger Tim: Thanks for the altitude heads up but this isn't my first trip to elevation. Highest so far was a week above 10,000' on the Grand Mesa in CO. Drink LOTS of water and until you feel acclimated, and even then, "walk like you're retired." :) I'll be there late April, is your North Rim suggestion still an option? I was contemplating heading north from VotG into Moab before heading back via Denver. Sounds like a few days in that area are worthwhile also.
Thanks again all.