Where to stay in Provence for 5 nights

Yes, at least 3 nights in Arles. We did 3 nights in Arles and 2 nights in Avignon. If I did it again, I would do 2 nights in Vaison la Romaine instead of Avignon.

We stayed in Airbnb in both places. We had a car in Arles and then dropped it off in Avignon since you don't need a car there.

We found excellent food and wine in Arles and great people watching.

If you have a car, stay around and just south of Avignon for the whole 5 days and do day trips from there. Everything will be less then 1 hour, 1hour 15 away from your hotel.

We can from Nice, but by train, staying in Arles , four nights, in early August. Hotel recommendation is Hotel de la Muette.
The french bull fights were on on the friday night, followed by the Saturday markets, both of which i'd
recommend. We followed Ricks "eating" recommendations.

I loved Arles (more than Avignon and definitely more than Aix en Provence), but I'm not sure I'd want to use it as a base with a car. Look into smaller towns (I didn't have a car, so I didn't get to these).

Consider Isle-sur-la-Sorgue. Its the "Venice of Provence" owing to the river that splits above the town, flows through in a number of branches, and reconnects below, leaving the town an oasis in otherwise Saharan Provence. Tubing or canoeing down the Sorgue river from Fontaine de Vaucluse is a must. Also very convenient to Avignon and the Luberon.

I've stayed in Arles and St. Remy. There's nothing wrong with Arles, but I preferred St. Remy. we found it easy to do day trips from there.