Recently I've had several requests from friends who have been traveling to Geneva on what to see/do. To avoid repeating myself, I've coalesced my responses into the following recommendations:
Geneva frankly isn't that much of a destination - it's more of a place to live than it is to visit. While you're there make sure to walk around and see the jet d'eau, some old/important churches, etc. but I think your best bet is to get out of town.
Lausanne is awesome. Check out the Olympic Museum along the lake, the Chateau d'Ouchy nearby, Place St-Francois further up the mountainside, and the cathedral / canton hall (an old castle) even further up. The train from Geneva to Lausanne is only ~45 minutes. Ouchy, at the shore of the lake, is a former fishing village that is now the summer destination of many of Europe's and the Middle East's rich and famous. Featuring a long promenade, this area is great for strolling and people watching.
For night life the major hub is the Flon district, a filled-in river full of restaurants, bars, and clubs. For good food my absolute favorite is Beau Rivage along the lake - the cafe, not the full restaurant. The full restaurant is Michelin starred and obscenely expensive. The cafe offers the same food and costs 1/3 as much - still not cheap given the damned exchange rate. Further up from Beau Rivage is the Croix d'Ouchy, a little less elegant but just as nice. For authentic Swiss fondue I recommend Cafe Romand near St-Francois or Cafe du Vieil Ouchy on the water.
Take the ferry across the lake to Evian.
Take a day trip to Gruyeres and see how cheese and chocolate are made.
Take the train or bus to Lutry and hop on the Lavaux Express, a mini-train that winds through the vineyards and stops for several tastings. Swiss wine is so-so and overpriced, but, when the weather is nice, this makes for a lovely outing.
Nyons and Montreux are particularly scenic with their chateaux right along the lake. If you go all the way to Montreux (another 15 minutes by train beyond Lausanne), you can see the iconic Freddy Mercury statue near the Jazz Festival location. He, Audrey Hepburn, and some others are buried there.
If you really want to take in many of the towns/chateaux along the lake, take a sunset dinner cruise, which will take you by each one.
What do you think, have I captured it or missed the mark? Any other recommendations to add?