Bruce...
There is the State Park site at the old gold rush town of Columbia - fun way to spend a few hours looking at the old buildings - several are usually open and sell food, candies, etc... or you can pan for some gold flakes there as well...
Jamestown has the Railroad museum with lots for the rail fan to see - they run some of the steamers once in while...
And up the 'hill' a bit, there's the Black Oak Casino...the Mi-Wuk's will be happy to have you stop by... ;D
Sonora has a few old shops and saloons to visit as well...for gishing you might want to try New Melones reservoir... http://www.gloryholesports.com/about_new_melones_lake.htm
Have a great time, the weather should be great...
Ray, near Stockton, CA