spending 3 days in provence area in september

Definitely wherever the local market is. I loved scenery around the area, but the images that are most vivid are from the markets -- the colors, the aromas, the people, the festive displays of just about anything. The market at Bedoin (at the foot of Mt. Ventoux) was fabulous! And while technically not part of Provence, my husband and I liked Nimes. The arena is definitely worth a visit as is Pont du Gard.

That's not an easy question to answer. It's a big area and with just 3 days I think it would be easier to decide what you want to see first and then use that to determine where your base would be for the 3 days. Picking a base (and deciding what to see) also depends on where you are coming from and where you are going to from there, what your method of transportation will be, what types of sights are of interest, etc.. Provence is full of scenic areas, ancient sights, small picturesque villages, wonderful markets, museums dedicated to art and artists and with only 3 days you need to be selective. I would recommend getting a good guidebook for the area (RS Provence, Michelin Green Guide to Provence, etc.) and study it. Do some online research to hone your areas of interest. Come back with more specific questions if needed.

We had a small flat in Lourmarin and used it as a base for day trips. It was ideal.

Any small place you stop can be a delight, however if you are limited to public transport, and keen for the more 'recognised' sights.

Day 1 Avignon (Pont + Palais des Papes)
Day 2 Arles
Day 3 Pont du Gard & Nimes (Arena & Maison Caree)

Aix-en-Provence, Les Baux, St Remy, Orange would be worth seeking out if you had more time.

One activity I'd recommend is Carrieres de Lumieres near Les Baux. It's a spectacular display!

If you like hiking, there are some great hiking options in the Alpilles region.

Arles, Saint Remy, Avignon, Nimes (Pont du Gard)...it really depends on what you most like to see and do! You probably can't go wrong!

We used L'Isle sur la Sorgue last month for a 7-day stay, and didn't come close to running out of things to see. So, the recommendations above to do some research to identify your interests make sense. We used the RS Provence book successfully. Sorgue is a good base for the nearby Luberon hill towns, although we ventured as far south as Cassis on day trips. The tip above on the Carrieres de Lumieres is excellent. This was one of our unexpected highlights; also easily reached from Sorgue (after a recommended stop in St. Remy.) The Sunday market in Sorgue is an eyeful if you enjoy that sort of thing...everything from an amazing array of food, to clothes, to antiques. My wife accomplished much of her gifts-to-take-home shopping here. (The market reappears on Thursdays, but is smaller.) Good luck!