However you decide to get to it, give yourself at least 4-7 days in the Dordogne (Perigord) region. And I concur that, although a lovely town, Sarlat is not the be-all and end-all of the area. We rented a place near La Roque Gageac for 10 nights in 2023 for our family of seven and filled every day, but had a relaxed time as well. We unfortunately didn't get to the eastern section of the Perigord this time (we have been there in the far past), so you have a wide range of locations to choose from. The Perigord comprises about 3500 square miles, so lots of choices to make (all good ones).
We drove from Bordeaux, where we rented a car, and took about 3 1/2 hours to get to our gite, using the D roads, but stopped for lunch along the way. We returned to Bordeaux to drop the car and took a TGV (2 hours) to Paris, staying 2 nights in Bordeaux at that time. (We had never been, so planned on this stop.)
We have also stayed in a few different places in Provence (including the Luberon part), and St. Remy or Arles are the home bases we liked best. We have never driven from that area straight to the Dordogne region so can't advise on that route. However, if you want shorter drives, find a place to stop for the night en route from St. Remy (or wherever) to your home base in the Dordogne region. Hubby can probably do this one nighter one time to shorten the drives.
Also, looking at your 15 days, how does this breakdown re itinerary sound? (Adding 2 days for arrival and departure per your explanation)
Day 1 Arrive Sleep Paris
Day 2, Take train to Avignon (just under 3 hours), rent car, drive to St. Remy de Provence (under 1 hour)
Sleep St. Remy four nights and explore area
Day 6 Drive to wherever you decide on in the Perigord in one day or stop overnight somewhere
along the way Sleep in Dordogne or interim town
Day 7 Dordogne exploration Sleep Dordogne 5 nights
Day 12 Drive to Bordeaux (3 to 3 1/2 hours, return car at train station and take TGV to Paris (Gare Montparnasse)
2 hours) In Paris mid to late afternoon, enjoy Paris, sleep Paris 5 nights
Day 17 Depart (or day 16 if I have figured incorrectly).
This gives you 3 full days based in St. Remy and 4 full days based in the Dordogne for sure. Also, 4 full days in Paris if you leave day 17. You also have, depending on when you leave a place, a half day at your arrival when you get there (St. Remy on day 2 and Dordogne on day 7, if a stopover on day 6, and Paris on day 12.) You can deduct days from Paris and add to Provence or the Perigord if you wish.
This is just a rough start at breaking down your itinerary....some ideas to build on, add to, subtract from, or just scrap. Hope it helps a bit.
