car rental outside Paris (input on my tentative itinerary welcomed as well!)

The advantage of Caen is that it gets you out of the Metro Paris area and allows you to start your driving in France experience with less stress. Also, from Caen it is easy to avoid free flow tolls which is harder to do from Paris. The car rental office is directly across the street from the train station there. Although our drivers knew how to drive a manual transmission, there was consensus that an automatic had been a good choice as there was just one less thing to think about.

We did a similar trip last fall and both my son and daughter-in-law said afterwards that they would have preferred more time in Brittany and less in the Loire Valley. It wasn’t that we didn’t enjoy the Loire Valley, they just felt that there was so much more in Brittany that they wished they had seen.

We drove from Amboise to CDG and it was stressful when we neared Paris. I learned to drive on Freeways and deal with crowded freeways and crazy drivers now where I live (Seattle Area). However, that still left me with plenty of stress driving through that traffic and navigating multiple lane and freeway changes. Traffic can get backed up in an instant. I wouldn’t choose to drive from Amboise to CDG on the same day as my flight if there is an alternative. We dropped off the car and checked into the Citizen M hotel for the night before our flight.

Thanks for your insights Carol- I will continue to read about Brittany. I am not sold on The Loire, though it sounds pretty. We do love the coast (we're from Vancouver). Last summer we did Nova Scotia and PEI, so you can see the ocean has a grip on us! :-)

Lisa,
Just re the car rental. Unless you are planning on stopping somewhere along the way to the DDay area of Normandy, I would take the train to Caen to get your car rental. There are far more rental opportunities in Caen, right across from the train station, than in Bayeux. Drive to Bayeux from there (about a half hour). You should be aware that driving to Honfleur from Bayeux is in the opposite direction from Bayeux to Dinan. So you would drive about 1 1/2 hours to Honfleur, then retrace your steps (a bit) to go to Dinan (about 3 hours driving).
You could also possibly take the train to Le Havre, get a car there, then drive straight to Honfleur (which doesn't have a train station). That only takes about a half-hour. Then on to Bayeux, then Dinan. No doubling back. The rest of your plans sound very doable. Whether you decide to go to the Loire Valley or not, I would drop the car at my last location before Paris and take the train to Paris. Dropping off at a different location shouldn't be too much extra, in my experience.

How many nights do you have in total? Remember arrival day and departure day aren't usually counted as "touring" days, due to jet lag, getting to lodgings and through immigration, etc.

lisa005, last spring we took the train from Paris to Rennes (picked up our rental car at the train station; lots of rental company options) explored Brittany/Mont St Michel. Then went on to Bayeux, Honfluer, Rouen and returned our car in Lille since we were on our way to Belgium via train.
You could return in Rouen then return to Paris. Returning at a different location but within France is a nominal fee and worth the convenience. If you decide you want to pick up Caen vs Bayeux, then Caen it is, as it has more options. Charming Bayeux is a fabulous place to stay but fewer rental car options.

We had a marvelous trip and know you will too!