.. and don't miss San Xavier mission. Somewhat ambitiously called the 'Taj Mahal of the Desert' but well worth a trip anyway. Just south of the city (on the way to the Titan silo).
If yoiu're into astronomy at all then Kitt Peak observatory (
http://www.noao.edu/outreach/kpoutreach.html) is worth a visit. About an hour's drive southwest of town.