Below is the response from my friend. I hope this helps a bit, she said she is very jealous as she would love to be going as well.
Some ideas for lunch time meals which are not too expensive and give choice: eating in the restaurant of La Placette, Le Centre, both big shops in town centre. Some have a terrace. Manora is on the Place St Francois, in the middle of town, no terrace. La Migros is another big shop with restaurant. They are popular at lunch times with the locals too.
For nice ice cream, Movenpick hotel, in Ouchy, by the lake.
For a good view (Lac de Sauvablin and its wooden tower offering 360 degree view, and some unusual walks, discoveries:
http://www.lausanne.ch/view.asp?docId=23940&domId=63838&language=E For some very fine dining:
http://www.lausanne-tourisme.ch/view.asp?docId=30664&language=E ideas of very nice restaurant. Have never been myself in any of them, sorry.
Visit the Olympic museum in Ouchy, walk along the lake side, take one of the big boats to visit other towns or just see the Swiss Riviera from the lake, or pop over to France (take passports)
Visit la cité, that is the old town of Lausanne, around the cathedral. Need easy walking shoes as there are some cobbled streets still about.
Transport is easy with le metro and buses (not especially cheap although with a day ticket, worth it: clean and reliable). In the evening, there is in Flon, the Tunnel, the area around Grand-Pont and Marterey, there is a lot of night life going around there with clubs and cafe and bars with all sorts of music. This is quite recent and new.
There are some nice museums and galleries, just in case the weather is not too good but not knowing what they are interested in, difficult to advise.
For sports, there are lots to do: rollerblading along the lake shores, swimming in the open air swimming pools and/or lake, (my favourite sport: sunbathing!) walking around as it goes up and down, jogging, pedalos, hiring a boat (sail or motor), cycling, shopping!?!.
There are a number of good websites with nice picture (makes me a bit homesick).
Not sure I helped.
Wishing them a great time!