What is the best city to stay in for such a short stay? What is a good basic itinerary for that many days?
I like Arles, vg and interesting town with vg lodging options.Gd transport hub and easy to see some wonderful villages nrby.
Arles is a firm favourite of the many good folk on this forum. Spend a day exploring there, then a day each for Avignon and Nimes, both less than 30 mins by train.
I stayed in Arles in late April and really liked it as a hub and we had a car.Lots of things toes in Arles and great restaurant options for dinners.
Avignon has a few decent modern hotels within a block or two of the central train station.
Will you have a car, or are you planning on using public transportation (bus, train) ?
Without a car, Avignon makes a great base, but I'd opt for staying inside the old City Walls in the old town. Be sure to visit the Les Halles indoor market! It's possible to make a day trip to Arles, or Nimes, or a Luberon Valley visit of towns.
With a car, and if you're doing a short-term rental of a gite or house, consider Saint-Rémy-de-Provence, a delightful town with its own markets (all Wednesdays, plus some Tuesdays in summer), just down the road from Van Gough's asylum, Roman ruins at Glanum, the hilltown of Les Baux. and the aforementioned, driveable Luberon towns.
I like St.Remy