Could anyone recomend a day tour from Paris to Normandy to see the D Day beaches?
While I'm sure you can arrange for a package tour that includes transportation from Paris to Normandy and back, you'll pay dearly.
If you want to save some money by getting to Normandy on your own, you'll be limited to an afternoon tour since you can't get to Bayeux by train before the tours depart in the morning. Overlord Tours (www.overlordtour.com) offers afternoon tours. You'll be done in time to catch a train back to Paris the same day.
I booked a day tour from Paris to Normandy through Expedia. It was pricey, (a little over 200.00), but this was my only way to do it for one day by myself. If you're interested, go to the Expedia site and it walks you through everything. They had activities for many cities, some were as cheap as 12 Euros.
We were in Paris in March and used Segway Tours for a trip to Normandy. They provided the train tickets and then we were met at the Bayeau train station by a tour guide and van. There were only three of us on the tour so it was excellent. Were able to see a great deal considering the time limitations. The driver then returned us to the train station. It was a long day - around 12 hr. or so - but well worth it.