I would HIGHLY recommend staying the night before and after in Bayeux. The Hotel Churchill is an excellent option, and is right where Battlebus picks-up. The Hotel Tardiff is also highly rated and is a few minutes walk away. The day before or after your tour, you can visit some sights in Bayeux, like the Cathedral (gorgeous from the outside) and the town itself (very picturesque) and the Bayeux Tapestry.
You can either drive from Paris (we drove from the airport, no problem at all). I used the turn-by-turn guidance from
www.viamichelin.com and it was unbelievably right on the dot. Told you where to expect to pay a toll and how much, gave you exact readings of what the exit signs would say (boy, that helped a LOT!). It is kind of a longish drive, but certainly do-able. The other option that is mentioned is to take the train from Paris straight to Bayeux. If you stayed at the Churchill or Tardiff in Bayeux, you wouldn't need a car at all.
Tell your tour guide in advance that your FIL served and is buried there. Give them as many details as possible and they will be prepared with any info or special sites they can figure out. People in this area love to know they have a relative in their midst! D-Day is still very much a big deal here, and it is refreshing how much Americans are loved in this area!
Also, CONTACT THE AMERICAN CEMETARY IN ADVANCE with your exact day of visit, what tour you will be on (they know all the guides well). When their is a relative coming, they do some special things. Usually there will be flowers on the grave (they actually have a local group that brings flowers out weekly and puts them on graves on a rotating basis). They also send someone down to the beach and bring up wet sand from where the troops came ashore. This is wiped onto the engraving on the tombstone. Against the white, white marble, the sand looks gold. It's a tribute to the family, and makes your photos come out excellent with everything clearly readable. When we were there (with a private guide that we hired because our youngest was too young to be allowed on the Battlebus tour) our guide was VERY excited to find one that still had wet sand in it. He was hopping up and down with excitement and looked all around hoping to find the family to express his appreciation to them (he was 3 on the day of D-Day, and was injured by shrapnel in the neck) but we couldn't find them.
Trying to "do it" on your own would be frustrating. It is one of those places where you get SO much more by having a guide. And the local guides really do a superb job and are extremely enthusiastic. Our guide commented that many people that try to do it alone mess up completely because the American Cemetary closes very early, even in the summer, so you can end up not getting in altogether unless you time things just right. And, as mentioned before by others, they get you there at "just the right time" so you can look around and be present as they play Taps and lower the flag (not a dry eye in the cemetary).
Reply here or Private Message me if you have any other questions or would like the contact for our personal guide. I can't figure out how to add an image here to show you what the gravestone looked like that had the family visiting.....but I know I could email it to you.