We had a great stay at the Agora Swiss Night hotel. It’s located about 1/2 block from the Grancy stop on the #2 Metro, which takes you down to the Ouchy/Olympique neighborhood by the water or into the city center and old town. It’s also a short walk, or one Metro stop, from the Lausanne Gare train station with connections to anywhere (not to mention all the shops and restaurants). The hotel provides you with a free Metro card, which you can request they send you in advance so you can use it to get there from the train station.
Another really nice thing about the Agora Swiss Night Hotel was the location of the breakfast room on its top (9th) floor - the view was spectacular! How can you beat breakfasting with a view of the Alps?