7 days in Provence, 3 hotels - too much?

On the plus side - you do have a car, so you aren't trying to use taxis or public transport...so you can stash your bags in the trunk (and hope for the best) and not worry about humping your bags around. But it still does take time to check out/pack/find your new spot, which is your concern. Personally, I'd do two changes - it's what we are doing in a few weeks - 4 nights in Salon to explore the areas to the east and north, 3 nights in Manosque to explore the more easterly area.

Of your places listed, my preference would be 4 in Aix and 3 in one of the others (disclaimer - we haven't visited St Remy or Gordes...only Aix - we are going to remedy this on our upcoming trip, so I don't really know what they have to offer).

You will be traveling between towns anyway, so the travel time "between hotels" seems moot? I like your idea. Im not one who finds "packing/unpacking" onerous, but I only take out my toiletries - my clothes remain in my bag and I withdraw what I need and put back in what Im not using. I understand there are people who hang clothes or put them somewhere else, but I am not one ;p
We stayed 6 nights, 4 in Il sur La Sorgue and 2 in Cassis (for the Calanques, which we hiked and boated to from town - there's a story). I think two would work just as well...

I would stay in Avignon instead of St. Remy. Last year we booked a place in St. Remy. Ended up leaving early and forfeited lodging cost to stay in Avignon. We stay inside the medieval city walls. Enjoyed it so much we stayed an extra night. We also had a car.

My solution to packin and unpacking for our 3 week trip to France was take 1 large suitcase and I decent size carryon bag each. Packing the carryon with 3 days clothes and leaving large suitcase in car. Only every other stop taking large bag in. And repacking for another 3 days in carryon. We are planning our month long trip to France for this September now. And plan on using same packing plan.

When are you going? There is quite of bit of ongoing construction in Aix and getting in and out has also been a bit of a hassle. You might consider a place like Lourmarin and use it as one base to go into the Louberon and down into the Calanques. Then, spread your next stop into the west/north -- St. Remy, Les Baux, Isle sur la Sorgue, Vaison La Romaine or Avignon.

These destinations are all close enough to be seen from a single base. The strongest argument for shifting your base, it seems to me, is to spend evening is a different place.

You could make the case for Gordes, but (in my view) the argument fort Aix is thin.

Just returned from this area and stayed in Gordes for 4 nights and St. Remy for 4 nights. We had a car and our preference was to stay in small towns in the Provence area....went to Aix for its Saturday market and thoroughly enjoyed it but it was a little busy and crowded for me. We stayed in Le Jas de Gordes on the main road into Gordes and would highly recommend it to anyone. It was wonderful. We loved the tree-lined drive into St. Remy and walking the town streets on the inner circle of the old town. We also made a reservation at Le Chateau des Alpilles for lunch one day while in St. Remy and I would highly recommend relaxing at a meal there as well. Its a beautiful chateau in the country outside St. Remy......a feast for your eyes!