A week in France

Hi, we'll be visiting France in June for honeymoon and that's after about 5 or 6 days in Switzerland. We wish to visit at least one more place in France before flying back from Paris. After doing some research and reading on the comments of VTers, we've shortlisted three regions - Alsace, Southern France (in particular, Nice) and Brittany/Normandy but are having a hard time deciding. We will love to visit beautiful sights (and don't mind travelling a little more for that) as well cities, but we are not so keen on too much of museums, cathedrals, chateaux, wineries. We will be travelling by train most of the time. Where will you suggest?

Thanks in advance for your responses!