France/Amsterdam

What is point A to point B? I am not following your question. Are you asking for advice on getting to each of the places in the sequence that you listed them in? Where in the Loire Valley do you want to go? Where in Provence are thinking about? I'd give you different advice if you were planning to go to Avignon which is western Provence or Nice, which is in Eastern Provence. Do you prefer mass transit or driving yourself?

Google Maps can show means of ground transportation between the cities (train, car, maybe bus but not planes.) ViaMichelin shows road maps, tolls and time estimates. If the trans-Atlantic tickets are not purchased yet, considering flying into CdG and home from Amsterdam, or the reverse, using a multi-destination search function.

You may also want to consider flying into Amsterdam and home from Nice or vice versa. That would cut down on transit times between your stops. If you have your stops listed as you intend to travel, you are going to waste a lot of time getting from Provence to Amsterdam.

Are you talking two nights these places? That is one day. This is IMHO way to much getting there to being there and it is expensive with little payoff. Provence is an enormous area -- 2 days doesn't touch it. One day in Amsterdam is hardly worth the cost of getting there.

We often end European vacations in Amsterdam for 3 nights/2 days because we prefer SChiphol to CDG. WE fly into Paris and out of Amsterdam or into Rome and out of AMsterdam etc. This is not more expensive and saves backtracking. It is easy to get to Amsterdam from Paris via Thalys and tickets are fairly cheap 3 mos out (like 35 Euro compared to closer to 100 closer to time of travel) I would drop one thing. If you want to do Provence I would train to Avignon, pick up a car and then slowly drive north back to Paris and drop the car there and take the train to Amsterdam and fly home from there.

If you have bought these tickets and they are not refundable, I would forget Amsterdam. Also,

Paris (4 days), Loire valley (2 days), Provance (3days), and Amsterdam
(2days)

Since you only have 9 days, I interpret this as actually Paris (3 nights), Loire (2 nights), Provence (3 nights), Amsterdam (1 night), plus a night in Paris before your flight. 4 of your days are travel days. Maybe it's Loire 1 night and Amsterdam 2.

I realize that travel days are not total losses, but they are not full day either. (A Provence > Amsterdam day would be a full day.) Checking in and out, getting about, sand settling in take time.

If you skip Amsterdam, and if your departure flight is in the afternoon, you can catch a very early train from Provence that goes directly to the airport in Paris in about 3 hours. This will save you a day and give you at least a little time in your 3 remaining destinations. I would do this Loire > Paris > Provence.

If you are tied to flying in and out of CDG ...
March 19 - Arrive Paris. Direct to Amsterdam (2 nights)
March 21 - Fly to Marseille for Provence (3 nights)
Air France AF1821 | dep 12:30 AMS Amsterdam | arr 14:20 MRS Marseille
March 24 - Train to Loire Valley (2 nights)
TGV 5368/69 | Avignon TGV dep 13:22 | St Pierre-des-Corps arr 17:29
March 26 - Train to Paris (4 nights)
March 30 - Depart Paris

Just a word of warning about not being in your city of departure the night before (re - Adam's recommendation - no offense to Adam)...tho train delays are rare, they can happen. If I had a flight home, I wouldn't wait until the day of to take a 3+ hr train ride to said city. Best to go the evening before - even if it's a late train. We took the TGV from Paris to Avignon in 2015, and there was a 'customer action' (aka, suicide by train) and our super-fast train was delayed by about 3 hrs - if any of the folks on the train were trying to get somewhere for something important - they were in trouble. Not to mention the time we took the train from Nice to Avignon and there was a torrential rainstorm - our train ended up being delayed by 2+ hrs.

Thanks all for responding! We are locked in at CDG as tickets have been purchased. (Black Friday deal: $500 direct flight from MSP. I couldn't resist ;) Our plan is to focus on the east side of Tours for Loire valley. Visit a chateau or two. For Provance, stay in Arles or Avignon for home base. We can drive or take mass transit. Having checked airfares to Amsterdam ($50), we might fly directly after arriving CDG at 0740.
CDG (direct to AMS) > Provance > Loire valley > Paris.
If need be, we can drop Loire and do it as day trip from Paris.

Yes to being in Paris the night before the flight. We were once on a Thalys from Amsterdam that came in 5 hours late with a load of people missing their flights out of CDG. Doesn't happen often, but it happens. Always be in the city of a high stakes flight the night before. I would not do this rushed a trip. But if I did, I would fly to Marseilles or Avignon on arrival at CDG (give yourself at least 4 hours from ETA to departure from Paris) and finish with Paris so the end of the trip is not wasting a day to get back to home base. And I agree with others that I would bag Amsterdam on this trip. We drove from Pont d'Arc to Auxerre this fall and then on to Paris the next day. It was a long day on the road, but you could certainly easily drive from northern Provence to the Loire. We have stayed at a little hotel in the Morvan forrest near Avalon twice Moulin des Ruats and highly recommend it. Near Vezelay and not far from Auxerre and it sits on a nice stream and has a very fine restaurant that attracts custom from the wider area. Adding the two Amsterdam nights to Provence and the Loire would make it a nicer trip.

Looking at DJP's proposed itinerary, it looks great in that it gives you the chance to see Provence and all the other places in your original post and takes into account the fact that you arrive and depart from CDG and avoids you having to get to Paris on your departure date. However, you should realize that you will get only one full day in Amsterdam because most of the 19th will be spent in transit and the morning of the 21st will be spent getting to and at the airport. If you are good with doing what we call in my family a bounce stop (bounce in and bounce out), then do it. Some stops on a trip can be just to take a quick look at a place. We did a bounce stop in Vienna between Dubrovnik and Budapest in 2015 and it was great. Bounced in late in the afternoon and walked around and went to a cafe, on the full day (day 2) went to the two things that we identified as our must dos for Vienna and bounced out on the morning of day 3 for an early train to Budapest.

I could well be wrong but I believe that it takes almost five hours by train from Provence to the Loire Valley. If I am correct about the train schedule, you’ll need to consider if you want to spend most of the day of the 24th on the train. I'd probably skip the Loire Valley as a multiple day destination and go straight from Provence to Paris (much shorter train trip and more frequent trains) and add a day to Amsterdam so that you leave on the 22nd and then leave Provence on the 25th on a train that leaves around 6 PM and arrive in time for dinner in Paris. Then you will have 4 full days in Paris and could consider spending one of them on a day trip/tour to see chateaux in the Loire Valley. In sum, I guess the thought is that you have too many places for too few days so drop either Amsterdam or the Loire Valley and I lean towards dropping the Loire Valley.