We will be traveling by car from the Avignon area to Antibes the first week of October. Planning to make a lunchtime/afternoon stop to see the Calanques. We will not be able to bring hiking gear and plan to take a couple hours to see what we can by car, stop to swim and have a meal. Considering Sormiou and a meal at Le Château which will be open again from August 25 to October 19. Open to other suggestions for a limited-time stop with a car!
Don't bother. You need at least one day to enjoy it.
Sormiou actually doesn't have great views. It's a pretty cove, it does have the best Calanques beach for swimming, but the scenery is not as dramatic as the rest of the area. Going there also makes you drive quite far into southern Marseille.
All links below lead to Google Maps.
If you are keen on seeing the Calanques and can do without swimming, you should park in Luminy, a campus near Marseille, and walk ~40-45 min one-way to the Belvédère de Sugiton on a gravelly path suitable with any shoes and any level of fitness.
Coming from the west, you should try to make time for the Route des Crêtes from la Ciotat to Cassis as well: the D141 road, starting here.
To reach all of these places, best to leave the A8 motorway in Le Cannet and take A57 & A50 via Toulon.
Then, as you leave Luminy to continue to Avignon, to avoid driving in Marseille take the Boulevard Urbain Sud leading to the A507 bypass.
@balso, I appreciate your thoughtful response! thanks for the tips!