I lived in Lausanne for six months. There are so many great sites and restaurants, picking a few is a challenge. But, here we go!
Places to Stay: I rented an apartment while in Lausanne, so I don't have great advice on hotels. However, I would encourage you to look outside the center city (where prices can be steep). If you find a place near public transportation, you can get downtown very quickly.
Good to Knows: These are a few tidbits that are just helpful (or fun) to know!
Good to Knows
Getting there: Can't really fly directly to Lausanne. You either need to fly into Geneva and take the train (which is located right in the Geneva airport) or you need to fly into Zurich (and take the train). Either way, train travel within Switzerland is top notch.
Getting around: Lausanne has excellent public transportation. A good tidbit is that most hotels offer free transportation passes to guests. Be sure to ask your hotel about this!
Lausanne is in the French-speaking portion of Switzerland. The locals really do like it when you (try to) speak French. Most people working in hotels and some in restaurants know English. But, smaller stores and restaurants probably won't.
As a heads up, most of the grocery stores in Lausanne (and Switzerland more generally) require that you use your own bags (or buy some on site). Have those bags ready!