South of France, October, no car

Vaison-la-Romaine is a bit challenging without a car: you can get there and back via bus without issues, but you won't be able to explore around.
2 nights would be the max I would commit to in such a case.

Nimes is a great base with good connections, you can add Aigues-Mortes to the list of day trips, and perhaps Montpellier.

As for Marseille, maybe 2 nights if you have not been?

We went to Vaison-la-Romaine via bus without a car, but it was a bit tricky getting there and even though we loved Vaison-la-Romaine we couldn't explore the other nearby villages since we didn't have a car.

Have you considered Isle-sur-la-Sorgue for your 2-3 nights in someplace smaller? We took a direct train there from Nice. You could do something like this all by train: Nice -> Isle-sur-la-Sorgue -> Nimes - > Marseille.

Thank you Balso and Christine! Your comments about the limitation of Vaison is helpful. I had looked at Isle-sur-la-Sorgue and will reconsider it.

I agree about Vaison-la-Romaine - visited after taking the bus from Orange. I think VlR is worth it if you are really interested in Roman ruins and/or you can be there on market day - which I THINK is Tuesday. Market days are great in Provence but the VlR market is less slick than fancier ones in St Remy and have old guys selling antique keys, farm equipment, lavender in cardboard boxes by the scoop along with everything else.

Arles is a favorite of mine along with Saint Remy. Arles has the Roman arena, theater and the van Gogh easel tour. Arles is an odd mix of really blue collar and charming Provence assertional with ordinary places alongside very charming little streets and plazas. Saint Remy is smaller and upscale with little shops and alleyways. Work to be in at least one of the towns for market day because it really is a thing.

Saint Remy can be challenging - I believe a 45 minute bus from Avignon or Arles (should be faster) is your best bet without a car. One of the problems is Les Baux is nearby and easy with a car but awkward without it. Even Glanum and van Gogh are walkable but much better with a car. I used buses for Vaison, and Pont du Gard on the trip I did without a car and rented a car for Saint Remy.

Finally visited Nimes and it is an interesting city to wander and it has a low key vibe and I enjoyed my time there. It is easily reachable by train from either Avignon or Arles but only some of the Arles trains are direct.

L'isle-Sur-La-Sorgue is a pretty and touristy town but is as close to the Luberon as you can get with a train. It is best from Avignon which is a trend you'll see for most things. Avignon is a pretty town with a lot going for it - a great permanent Les Halles market, tons of little plazas with restaurants and a pretty shopping area complete with marble streets. But like many people here I just don't "vibe" with it for reasons I can't really explain. But there's nothing really wrong with Avignon and it transport and tour hub of the area so it often makes sense to visit and maybe you'll like it - many people do.

Have a great trip,
=Tod

I second St. Remy, so much to do in the town itself and easy to get to by bus. Don't miss the Van Gogh walk and the Asylum. It has a wonderful market too. The Glanum archaeological site is close and walkable from the town too.

Thank you Hiredman and Susanking for very helpful suggestions and observations. I have ruled out Vaison but still deliberating other choices.

I just got back from Provence. My trip included many of the places you mentioned. I used Avignon as a base and found it to be excellent. There is a lot to see and do in the town itself and it has an easy to navigate train station. I'd recommend it and would visit it again. Uber works well too.
Nimes was a nice day trip, as was Pont du G.

Have a great trip!
Lee

I am going to be in Provence in late September to early October. I am using Avignon as the base mainly from public transportation perspective to make day trips to other towns. I am renting car for the last portion of the trip and plan to stay somewhere near Luberon and explore Cotes du Rhone and Luberon villages before driving through Verdun Gorge to Nice and drop off the car. The main reason for renting the car for this portion is because of lack of public transportation.

Thank you Pam and Veryspecialquilits! I'm glad to hear your more positive thoughts on Avignon which I may now reconsider.