Once I start walking, I find it hard to stop for a day....So my rest days are very short stages followed by lazy afternoons. I had a fabulous one in Lauzerte, staying in the Gite Les Figuiers (one of my favourite gites). Arrive early. Leave your pack by the gite and go have a long fabulous lunch. Back to the gite to check in (and because it was a rest day - I had reserved a single room) and rest! Beautiful village, great gite.
For me the best 'rest day' would be in a village big enough to have a couple of coffee and eating options, and a boulangerie, but small enough not to make me feel like I should be doing significant sightseeing. A single room is nice but not necessary.
Montcuq, Lauzerte, Lectoure, Auvillar, Le Romieu.
And then there are the VERY lazy afternoons at the gites in the countryside - no village, just the gite. I had a very nice afternoon with some other pelerins at Gite Maison Labarbe in Lanne-Soubiran. The house was for sale last year so I am not sure if the gite is still open.
Another gite that would be very good for a partial rest day would be the gite in Saint-Antoine just after Auvillar. Very small village. Gite has a great garden. There is a good restaurant.
One of the differences I noticed between the Le Puy route last year and the VDLP this year -- many more chances in France to stay in a place outside of a village or town - in gites on farms or just in houses in the countryside.
ml