Thank you all for your suggestions. My quick look at The Weather Channel says sunrise around 0650 and sunset around 1820 for the days we are there. We are arriving on Friday around 1700 and I have only parts of Saturday and Sunday (I do want to join my co-vivant in the spa since the trip is her birthday gift for me). So my plan would be to travel the City on Saturday morning and to the two Missions on Saturday afternoon. Sunday: tackle the National Park. While I like older buildings generally, I am keen on abandoned ones; the untellable stories they hold are intriguing.
I am still trying to get maps for Tucson and Arizona to get a better idea of distances and times.
Brian