I've done Tucson in November and December 4 times-- a really nice metric loop including the Saguaro NP, one attempted (& aborted) climb up Mt. Lemmon, and lots of miles on the greenway paths. The issue for me, being from the east coast, is that it's always hot and water becomes a premium. Last year I was on the greenway and 40 miles in I missed my cage and my only cycling bottle rolled off the trail into a 20' deep wash with steep concrete sides. No way I could get to it. So I had only a gatorade bottle with a threaded cap, which meant I had to stop to drink. On the trip up Mt. Lemmon a few years ago, I had planned on a trailhead where water was supposed to be at about 8.5 miles up from the base, but there was none to be found there in early December. I ascended up a few more miles until I was parched, and then just turned around and rode back down to a gas station to rehydrate.

If I go back I'm taking my hydration pack.