I am looking to spend about a week in the South of France, traveling from Barcelona to Geneva. What are the key cities that I should stay in and/or visit? Thanks.
Two typical stops would be Monaco and Nice -- though to protect your budget you'll probably want to stay in Nice, and just see Monaco on the way through.
For a less often recommended option, consider EVIAN-Les-Bains. This is the same Evian that lends its name to the bottled water. Very nice, relaxing, mountian setting spa town -- connects to Lausanne via ferry accross lake Geneva, and is 90 minutes by train from Geneva.
The whole area is lovely, and you might have a memorable time in any number of places.
Personally, I would plan to spend the bulk of that time in Provence, preferably with a rental car (which I would return before proceeding to Geneva by train).
Chamonix and Annecy are two beautiful places. Mont Blanc and the Aguille du Midi lift in Chamonix are amazing. Annecy is a picture perfect canal filled small city on a beautiful mountain lake.