Around 50 minutes with cost CHF 25 by train from Geneva Airport, Lausanne is situated on the northeast shore of lake Geneva.
I like walking. Therefore even it's extremely cold, I woke up early, walked along the shores, and found some spots to enjoy the view of the lake and the mountains at Ouchy. It was so peaceful. By the way, the headquarter of the International Olympic Committee is located next to the lake in Lausanne. 
The city center of Lausanne is in the valley, making the city even more unique and beautiful. I bought an one-day ticket, CHF 8.6, to visit the city by bus and metro as far as I wanted. One thing I was eager to do in Lausanne was to listen to the live Jazz. However the Jazz bar, Chorus, was closed due to the holiday season. Maybe next time... 
More photos for this trip in Lausanne:
Lausanne Guesthouse & Backpacker http://www.lausanne-guesthouse.ch/indexe.html (Strongly Recommended; very clean; great location)
Montreux (***)
Montreux lies on the northeast shore of Lake Geneva as well, taking around 20 minutes by train from Lausanne. Suggested by a gentleman in the hostel, instead of taking the train directly from Lausanne to Montreux, I transferred twice at Puidoux-Chexbres and Vevey, taking 35 minutes in total. The ticket cost CHF 11.8 while the direct train back cost CHF 10.2. For sure the view on the way worth the time and money! Comparing with Lausanne, Montreux is more touristy, but closer to the mountains!
Because it was cloudy, I didn't take the train up to Les Rochers-de-Naye Jardin Alpin (2042m). Instead, I spent some time hiding in my personal spots to enjoy the air, sound, and views of the amazing lake and mountains, and getting lost in the old city to overlook Montreux. 
More photos for this trip in Montreux:
Geneva (**)
Geneva is the second most populous city in Switzerland. Before climbing up to the northern tower of Sant-Pierre Church, I was kind of bored of the city. During winter, it's not very vivid in Europe. However on the tower, I overlooked the city and thought Geneva is not so bad somehow. I wrote my diary in the cold... to feel myself alive...
It was cold and raining, so I found a nice cafe and hope a hot chocolate would keep me warm. However it ended up with an ice cream costing CHF 9... although I got a running nose already... I enjoyed the ice cream a lot... :)
More photos for this trip in Geneva:
http://picasaweb.google.com.tw/aprilhsutw/SwitzerlandGeneva2008
Accomdation:
HI - Geneva Youth Hostel http://www.hihostels.com/dba/hostel055035.en.htm
Accomdation:
HI - Geneva Youth Hostel http://www.hihostels.com/dba/hostel055035.en.htm
建議可在Hotel/Herberg De Smidse享用晚餐，生意很好，不妨經過時就先預約，我是在前面有老奶奶時代梳妝台那兒享用晚餐的，但後來聽說後面dinning room的view比前面好，預約時不妨指定看看，記得四周走走，通往洗手間的走道不錯。根據一位可愛熱情的奶奶說，這間旅館餐廳已經經手祖孫三代，她和她老公每幾年就會來住一次，這樣也已經三四十年了。
餐廳前那條路的對面是一片草原，很多人會往那邊走，我還沒走過，但應該是通往某個不錯的地方。