Make sure you watch movie: The longest Day before your trip.
Then, after your stay in Caretan, mosy on over to the Pegasus Bridge:
http://www.memorial-pegasus.org/mmp/musee_debarquement/index.php?lang=uk
The museum is pretty neat, and getting to check out a HORSA glider is a VERY cool thing. then, go to the first Cafe liberated in France -- the one on the western end of the Bridge: the Gondree Cafe.
For me, understanding the sheer size of the the attack didn't happen until I drove from the Ouistreham to Ste. Mère-Eglise. It's a long way indeed by car.