1. Kartchner Caverns, because I've never been. [What's the planned trip on Saturday like? Can I take my car instead and scoot out afterwards to further explore the area?]
2. The Desert Botanical Garden in Phoenix. Yeah, it's a two hour drive, but damn, those are some great gardens. Afterwards, head on over to Mesa for some fantastic Mexican food at this place whose name I can't remember. Wow, that was a helpful tip! Thanks Chris!
3. Eating at Karichimaka. My aunt Lisa grew up in Tucson and this is where she went out to eat as a kid. The place is still there and has hardly changed; it's good home Sonoran cooking, nothing fancy, out in the middle of nowhere. Beer and wine only, alas; no margaritas. Try the carne seca tostada grande.
4. Eating at El Cid in Nogales, Sonora / buying tequila / enjoying watching senior citizens buy their meds South of the Border / being offered someone's sister, "she's very clean" / etc. [bring your passports!]
5. The Santa Cruz Chili Company in Tumacacori [I always seem to take some home, but never actually cook with it]
6. Going to Raging Sage and buying coffee to take home. It's good!
7. Mission San Xavier del Bac - for those of you who didn't grow up in the West, it's interesting to remember that a large part of the USA used to be Spanish... way back when
8. Driving around Tucson looking at old motels from the 1950s - the heyday of Tucson's tourist industry. A block or so west of the Venture-N you can find the old road through town, lined with a bunch of kind of creepy, architecturally sometimes very interesting motels. Very American. I also am fond of the Ghost Ranch Lodge, a 1941 tourist ranch with funny old cactus gardens. If you see any Arizona-themed gift shops, be sure to stop in and stock up on cactus candy and stuff like Reg Manning books [cf. What Kinda Cactus Izzat?].
9. If you're into the whole ecosystem kind of thing, it never hurts to check out Saguaro NP on either side of the city; the western area has a very interesting visitor center with plenty of info on how a desert actually works.
10. Finally, before you leave, be sure to stop by Tania's and stock up on Sonoran tortillas and carne seca. They freeze pretty well, so you can have burros for months if you're so inclined.