If you are looking for some after-hours fun in the Lake Tahoe area, there are a variety of bars, events and places to hang out into the early mornings. Most place at Lake Tahoe are laid back, local-style bars, but you will find some dance clubs like the Vex at Harrah's in Stateline, the Opal at Montbleu or the higher-end Cottonwood in Truckee. The nightlife in Tahoe is more for the after boarding crowd rather than the apres ski crowd. However a lot of bars like the Fat Cat in Tahoe City and the Red Dog Saloon in Virginia City will have some great live music.
Places like Pete n' Peter's is great for hanging out with locals, shooting some pool or darts and the Bar of America in Truckee is where you might see some local and national celebrities. Visit the Genoa Bar in Genoa, NV which is the oldest working bar in the state and come complete with the original spider webs on the ceiling and some artifacts from the late 1800s. The Divided Sky in Meyers near South Lake Tahoe is a little more laid back and less known, but features great drinks, food and some local bands.
If you want a little more culture (with a glass of wine included) you can hold out until the summer and make a reservation at the Lake Tahoe Shakespeare Festival. Thousands of people every year attend this popular event where the Bard is performed on the shores of the lake. You can bring your own picnic and a bottle of wine and make it a real night out.