Ohh you are going to LOVE lake tahoe! It acutally hasnt been that cold yet, although it did snow last week, today it is almost 80 degrees in Reno which means it probably around 70 still up at the lake. Just be prepared for anything weather wise, its always a joke around here about the weather and how fast it can change!
Here are some of my suggestions: For a really nice dinner on the lake there is a restaurant name Garwoods. The restaurant is right on the lake, its a little pricy but a great place for a romantic dinner! Jakes on the Lake is also really nice.
You can drive to Squaw Valley, they have a tram you can take to the top of the mountain, I dont know if it is up already but they have ice skating up there, restaurant, its really beauitful up there.
South Lake is a good place to go if you want to take part in some of the gambling and hotels. THey have lots of shops and such you can walk around in as well. You can also drive around to Tahoe City and they have nice shops and restaurant to eat at as well.
Let me know if you are looking for anything else in particular. There is a lot to do up there and around the area. You will love it, its beautiful!!