Don't go swiming in the lake unless you like real cold water.Also I can't recommend driving around the lake. Takes forever and limited views in most places. I would head over to Crystal Bay where the casinos are pretty much unchanged in the last 40 years. Crystal Bay Club - Cal Neva - Tahoe Biltmore, which was previously the NV Lodge.

The Bonanza ranch is a good activity if you have kids.Has gun fights, pancake breakfast, etc.

Mackinaw fishing is good.

There is a tram at the Heavenly Ski Resort. Provides a good view, but you can get pretty much the same thing going to the top of Harrah's or Harvey's. I would stick to these 2 casinos for south shore gambling. However my wife is very partial to the Ethel M chocolates store in Caesar's.

Not much in the way of shopping. 2 good golf courses, one at Incline Village and one at South Shore by the casinos. For cheap golf with great views play the course across from the Tahoe airport. Lots of good hiking (not ez walking) over near Vikingsholm in Emerald Bay. You can walk down to the house from the highway or can head into the hills (much tougher). Here is a link to Vikingsholm:
http://www.caohwy.com/v/vikiholm.htm