Arles is compact and easily walkable . . . there is a very well preserved 2000 year old Roman Arena (amphitheater) and a first century BC theater to see.
The thing I want to do the most is to get a booklet you can get at traveler's information centers that shows how to take a walking tour of Van Gogh's Arles. He lived there during a very productive time . . . lived in the "yellow house," was a roommate with and fought with Gauguin, had the breakdown that led to the famous ear-cutting incident, and painted my favorite scene, "Cafe at Night" (which I have seen the original of at the Van Gogh museum in Amsterdam and have a reproduction from there in my bedroom).
Arles has set up "easels" at places where Van Gogh painted a scene, with a reproduction of the painting and some description of what he was doing there. Having seen and enjoyed so many of his paintings, I want to feel that I am experiencing some of the exact views and feelings he might have had during this very creative time in his life. If I end up renting a car rather than taking the train, I might go to St. Remy, where his life ended (and where he painted "Starry Night" and many other spectacular paintings).
I've never been to Grenoble, but it looks a little far from Marseilles to do in a day.
