Marseille: it's out of the way, but friends want me to travel there......even for a one-day layover.
Is 1 day in Marseille worth it?
How far out of the way and what do they want to see?
Marseille was the one city in France we cut our trip short and went somewhere else (but we were traveling with kids who really needed a break and wanted another beach day). That being said, there's a vibrancy to Marseille that's different from the touristy parts of southern France. The kids loved the Tunisian restaurant we ate lunch at and shopping in the old port.
If you do decide to do the one day consider just using taxis so that you don't have to waste time hunting for parking.
There is a Bourdain episode on Marseilles, and a Bizarre foods episode just to show you some cuisine and a favorable view of the town. We found it had its own charm and absolutely fascinating history and things to see. We were glad to spend a day there.
Marseille was my gateway airport to the Riviera. As long as I had to be in Marseille to get to Nice, I decided to spend 2 nights there (1-1/2 days) and I was very happy I did so. I probably could have found more to see/do if I'd spent another day there.
To me it seems like a crime to only spend 1 day there - but it's better than nothing! Allez-y!