There's not much right in Tombstone and weekends are more active. However, plenty to do in the outlying areas.
The Queen Mine Tour is open and is in nearby Bisbee. It's highly recommended and is given by former miners. You don a yellow slicker, helmet with a light and get on the mine car for the tour. No walking needed.
http://www.queenminetour.com/Kartchner Caverns State Park also has an excellent tour of a living cave and very professionally done. It also has a very nice campground with electric.
Lots of nice hiking in the Sierra Vista area. The Chiricahua Nat'l Monument is very unique and hiking is great.