Okay - I live in Reno, close to Tahoe, finally something I actually know a little something about
Ponderosa Ranch closed several years ago.
Over the weekend Tahoe got a couple of feet of snow so the skiers and the resorts are happy. The resorts cater to everyone and all skill levels. You could take a family ski lesson or just ride the gondola. The gondola ride is breathtaking but be warned, the top of the ride is close to 10,000 FT and the air is thin up there. Heavenly also has a zip line ride that is supposed to be incredible. Remember to drink lots and lots of water while you are here.
Will you be renting a car? If the weather is decent maybe plan a day at Squaw Valley. They have snowtubing, ice skating, a cable ride and you could even take a dog sled ride etc. Plus, Squaw Valley is beautiful and not quite as high as Heavenly.
Truckee, CA is a fun little historical town with lots of shopping, restaurants and as a previous poster stated the Donner Memorial.
Virginia City is worth seeing IMO. We need the tourist bucks
It was recently named one of Americas 12 most distinctive destinations. The businesses are a little cheesy and touristy but the mine exhibit and the V&T Railroad are worth a visit. Pipers Opera House, the old cemetary and the church are beautiful and full of history. Since March is off season, I would call ahead and make sure the things that peak your interest are open.
In Carson City (state Capital) there is the Nevada State Museum with a lot of mining history. We went there when DS was in 5th grade and it didn't hold anyones attention for very long. It's an old museum and it feels "old". I have been driving by the railroad museum for 15 years and have never been.
Sierra at Tahoe offers lots of family adventure and is closer to S. Lake than Squaw. There is always the option of buying an inner tube and finding a hill.
The Red Hut Waffle Shop is famous and a great place for breakfast. IMO skip Heidi's not worth the hype. The casinos offer cheap buffets but not necessarily good food. We prefer the local restaurants anyday.
At the base of Kingsbury Grade in Genoa, NV you will find Wally's Hot Springs. Nice place to spend a day soaking your cares away. It is a quick but steep winding road down from the lake.
Here is a list of several sledding/tubing options.
http://www.bluelaketahoe.com/visitors/recreation.php?s0=17&s1=103&s=47&l=2
Honestly, Reno doesn't have much to see in the winter. The parks in and around the Truckee river are nice and the summer art festivals and kayak events are a lot of fun, but March......heck that is when we locals all bail out and head over the hill to San Francisco or Los Angeles (
DisneyLand) we have been snow bound all winter and want out!
The car museum is interesting if you like cars. The Museum of Art is nice but if you are used to big museums then Nevada Museums are not really an attraction We go to California for our "Brain Candy"
Reno's lates claim to fame (Sparks, actually) is the Scheels all Sports store. 298,000 sq. ft. of sporting goods. The place is massive. You can also ride the ferris wheel, or take a spin in the Nascar simulator.
http://www.scheelssports.com/webapp/wcs/stores/servlet/ScheelsStoreView?langId=-1&storeId=10001&catalogId=10001&storeLoc=RS
Pyramid Lake is unlike anything I had ever seen. Go thru Reno and it is another 45 min or so to it's shores. That would be 2-2.5 hours from South Shore.
http://en.wikipedia.org/wiki/Pyramid_Lake_(Nevada)
Sorry, I got a little carried away - Happy Planning and I hope you enjoy your trip.