I will be in Paris for 4 n. In the grand scheme of our trip, I had to give something up to make the entire thing work, and it was the 2n in Bayeux with the intent of visiting Normandy Beaches (I don't car about the shroud). I've read some opinions on day tripping it, but it seems like the general consensus is that its just too much for a day trip. In my mind I would want to leave early am, rent a car and drive up and back the approx 70 miles of coast, stopping and getting out here and there, then hop and a train and return to Paris.
I believe the train ride is something like 2-2.5 hrs each way, so that 4-5 hours of just trains...
What do you think, is that too much? Has anyone ever done it?