San Carlos is worth a peak, IF you aren't in a hurry (plan 2 extra days). Otherwise, just do as Steve suggests and stay in Hermosillo. Driving south, there is a Holiday Inn on your left. Its $70 a night (expensive for MX), but the security is excellent. One of the few places it was easy to pull in with a truck and trailer.
Walking back North from the Holiday Inn, on the left side of the street is an excellent restaurant. I can't remember the name, but its just a few blocks from the HI and it has an outside seating area with a fountain. I plan to eat there on my next trip in a few weeks.
(This post was edited by ncferret on Sep 1, 2005, 4:02 PM)