I'm also in Tucson, though in a different part of the city. I haven't done much recreational riding since I got here (that will change as soon as I pass my comprehensive exams!) but the absolute worst part of my commute is a residential street. 2-lane, no shoulder for part of it, and people seem to use it as a shortcut to get to the north-south route with less traffic than the major north-south road on this side of town. Now, I'm also trying to get to this road. It's got a wide bike lane all the way down to the bike path access point, and it's new pavement. I see plenty of cyclists on it on my way to work (not so many on the way back), so drivers are pretty good about it. The Loop isn't such a great option on weekends unless I leave early and it's winter, but it's fine on weekdays. Except winter afternoons, when you get the packs of roadies who use it as a shortcut and take up the entire path.