Being out of the league of "money is no object", I might suggest that Bayeux, as Al suggests, is one spoke for the Cotentin. If they have kids, the chateau in Caen is good for letting them loose and burning off steam running around. According to my friend, the new museum of Liberation in Caen is well worth going to, but more of an adult thing. I would tend to avoid staying in Caen because of the traffic, even with the new beltway. Liseux is another hub if you want to explore the Calvados area. Down towards Mont St Michel, I have recently found that Fougeres is not a bad hub, which also gives the option of nearby St Malo, Dinan, and Rennes.
Now, where to stay. I tend to prefer the Gites, but if money is no option, how about the more opulent ones situated in old chateaux or manoirs ? I forget the name of the grouping, but they are very classy B&Bs, and if its the right place, provides opportunity to interact with some very interesting people. Having dinners at those places is also an option.
I would further suggest that they get a NAV system in the rental car, especially if the hotel is out in the country. Also, many of the old cities are a maze of one-way streets, and the signing for route directions in cities is many times confusing because they assume that you already know the area. Make sure the NAV has the option for English if has audio capability.
Joe
