Hey there,
I've been having the same debate and would love to hear what everyone is thinking. Here are my thoughts:
On one side I've been told by several current HEC MBA's that living on campus is the way to go for the first 8 month, core period. Commute-wise you save a lot of time and it is a great way to get to know your classmates. But, having lived in Paris before, I was a bit shocked by the prices they are asking for a small place well outside of Paris. An apartment nearby would be much cheaper and an apartment in a nice area of Paris would probably be the same price or cheaper. That said, navigating the housing market is a pain (especially if you don't speak French and need something short term), but maybe that is something HEC can help with. The commute to and from Paris would probably take between 30-60 minutes depending on the part of the city (anywhere near the RER C would be a big plus).
That's everything I've been taking into account and I still haven't made up my mind. Although I'm leaning towards the campus option. What are other people thinking?
-Nick