Need feedback and advice on our 20 days itinerary

I would just concentrate on France at a bit more leisurely pace.

Apr 24-27: Paris
Apr 28-29: Normandy
Apr 30: Mont St-Michel
May 1-3: Loire Valley (sleep in Amboise)
May 4: Bordeaux
May 5-6: Biarritz
May 7: Carcassonne
May 8-10: Arles
May 11-13 Nice
May 14 Return home.

Hi, I can see a little bit of a problem between the time you leave Amboise and arrive in Carcassonne. You have set up several days of driving with little or no time for seeing anything. The drive from Amboise to Bordeaux will take most of a day. Then you get up the next day and take a big chunk of the day to get to San Sebastian. After Pamplona you have several hours on the road to reach Carcassonne. I think you're setting yourself up for a pretty tough trip through that part of your itinerary. It could be that you're reaching too far to try to incorporate Spain.

Bruce

Use viamichelin.com to estimate driving times, then add for stops and possible delays. You will save time by using the toll roads, but it probably won't be as scenic and you won't be passing through quaint villages and charming sights. GPS is a good idea for driving in France.

Thank you so much for your advice. After we decide to skip Spain and concentrate in France. Since we will not go to San Sebastien anymore. Is Biarritz worth seeing or I should also skip Biarritz and spent more time in French country side and small villages?

I think that is up to your personal preference.
The beach at Biarritz offers a nice contrast to the other beaches (Normandy and Cote d'Azur) included in your itinerary. The coast is also a nice contrast to country villages/scenery.
You could schedule the Dordogne (Perigord) instead.

I suggest that you add one of the days that were going be in Spain, to Bordeaux, in order to make a daytrip to Arcachon. It's a charming town. When we were there, the TI Office was offering walking tours of the neighborhoods where wealthy 19th century Bordelaise built summer homes. If still available, I highly recommend. You can also get boat rides around the bassin.
Near to Arcachon are several beach resorts. However, the best attraction is the Dune du Pyla, a massive (1.7 miles long) sand dune, which you can climb (347 ft high). Great views from the top.
Of course, you'll want to eat a great seafood meal.

WE like to base even if it is for two nights -- That way we aren't stopping at important sites with our luggage in the trunk which is always a gamble. We never leave things like ID, computers, cameras etc in the car and it is a pain to have to schlep a heavy messenger bag with those things every time we want to visit a new site. We also like to alternate one night stops with 3 or 4 night stops as one night stops tend to eat up too much time on logistics.

Should we spent 2 nights in Bayeux after visit Honfleur? Honfleur looks very nice but I think I maybe easier just spent 2 nights in Bayeux. Rick Steve suggest to spend one night in Honfleur and one night in Bayeux.

I may consider adding Dordogne to my plan.