Change in plans trip to Provence

Strike or no strike - too early to tell for a May vacation! - your idea is a good one as long as the extra cost is not too much. Since your trip is Provence-focused, there is no need to go to Paris at all.
But rather than Nice, could you fly into Marseille? There are virtually no direct flight between Nice and the US (seasonal NYC flight excepted) so it does not change anything in terms of travel hassle, and it would put you much closer to St Rémy/Avignon.
If you do fly to Marseille, spend the first night in Aix and rent a car in downtown Aix or at Aix TGV station the next day.

If Nice is your only option: I would rent the car on arrival and drive 15 minutes to Cagnes-sur-Mer, which is cute. If your energy level is OK, you could visit St Paul de Vence, too. Then I would aim to spend two nights in Nice on your way back, because it is worth it.
If you really do not want to drive for any distance upon arrival - which I totally understand, then for one night I would just stay at the OKKO hotel right by the airport (or any other one), go to central Nice for the afternoon, and rent a car from the airport the following morning. No need to travel to central Nice with your luggage just for one night.

Thanks so much Balso. Right now Delta is flying non-stop from Atlanta to Nice. We will be flying out of Asheviile NC connecting through Atlanta so that flight keeps us out of CDG. I like your idea of getting the rental and then staying near Nice the first night. This plan avoids the trains by renting a car for the entire trip instead of taking the train from CDG to Avignon. We will need to shuffle our reservations around as we had planned on staying in Avignon for the first 4 nights and travel by train to the Arles and nearby. I know we will need to hassle with parking to visit Arles and Avignon.

Well I had no idea about ATL to Nice!

Regarding places to stay: you could stay in Uzès or in the Luberon for 3 nights (both lovely areas), and perhaps extend your Saint Rémy stay by 1 night to make it 4 nights. That would provide good balance.

As for parking: in Avignon it is no hassle, there are plenty of parking garages around the perimeter of the old town. Palais des Papes and Oratoire parking lots are very convenient. Arles also has a very central parking garage near the boulevard that skirts the southern edge of the old town (inaccessible on market days), and another one on Place Lamartine which is less central but more convenient IMO.

Yes Balso that route was not available when I started planning this trip. Delta must have added it. I need to stay with Delta as our original flight through Paris was with Delta (we can change). Based on your suggestion we may keep our Avignon stay as we plan to see the Roman sites in the nearby towns.

It depends where you are staying in Avignon: you might not be able to park close to your place (the old town is basically off limits to cars), and when I say "parking in Avignon is no hassle", I mean it from a day tripper's standpoint.
Personally, with a car I find it better to stay in a town outside Avignon, and go to Avignon for the one day that you'll need to see the city (you do not need more). If you are willing to share where on Avignon you could be staying, I could try to be more specific!

We will be staying in the old town north end. We would be totally up to staying outside of Avignon. Any suggestions?

This past summer we found it very easy to drive into Avignon and park. There is an enormous underground parking garage under the plaza in front of the Palais des Papes. You enter it just off the major boulevard that circles the city so really no navigating any smaller city streets.

You also mention staying in St Remy. In case you need parking I will also share the "secret" entrance to the very large parking lot there https://keithvansickle.com/secrets-of-st-remy-parking/ Mr. Van Sickle has other great Provence tips on his blog that helped us.

Enjoy the planning!

Thank-you so much Laura Ann. I have read about the secret parking lot but this gives a higher level of detail. We are staying outside of the town so this will come in handy for parking for going into town for dinner.

Have flown into Nice several times. Wonderful to stay first night (or two) in Villefranche. Then continue for your Provence adventure!
Drove once from airport in Nice up to Carpentras - was falling asleep and needed to stop for expresso! From then on, we stayed near Nice first!

Thank you Marna for the suggestion. We will not be driving but to get somewhere close to the airport. Balso has a nearby suggestion also. Did you fly back out of Nice? Is it easier to return the car to the airport the day before the flight and stay close or return the day of the flight? Flight leaves Nice at 1100. I have not researched transportation to the airport...train, tram, bus or taxi.

We will be staying in the old town north end. We would be totally up to staying outside of Avignon. Any suggestions?

So you could be close to the Les Halles paid parking lot, or the one at Palais des Papes. It will cost some money, but I don't expect daily rates to exceed 25€. 30 at worst.

If you want to look at places outside Avignon that are not Saint Rémy: Villeneuve les Avignon is one, just across the river from Avignon and often overlooked, it has monuments of its own. Further afield, Uzès to the NW would provide good access to the Roman sites of Nîmes, Pont du Gard and Orange. And to the East, l'Isle sur la Sorgue and nearby Pernes les Fontaines are charming towns with good access to Avignon and to the Luberon.

"Did you fly back out of Nice? Is it easier to return the car to the airport the day before the flight and stay close or return the day of the flight? Flight leaves Nice at 1100. I have not researched transportation to the airport...train, tram, bus or taxi."

We have flown back out of Nice and I believe did return car day before, and stayed near the airport to fly out the following morning. I believe we had an earlier flight than yours. Probably at a hotel that had a shuttle to airport.
On another trip, we arrived in Nice, picked up car there, and dropped off in Avignon when we picked up a Viking River Cruise from there to Lyon.