My brother in law and I are going to tahoe from Dec 15-22 and flying into reno. This is the best bus/shuttle option we have found to get to our hotel in Stateline:
South Tahoe Express| Reno Tahoe Shuttle|Reno Tahoe Airport
Once there they have busses that go around town.
There are also busses that leave a few days a week to go to other mountains in the area like Kirkwood, Northstar, Mt. Rose and Squaw Valley:
Enjoy your time out there.