As an ex site owner in France, personally I hated them as I was lucky enough to be able to keep my site full without giving any discounts!
OK if you like going to sites, but personally speaking these days I/we have become so accustomed to going to Aires throughout France which are either free or at the most only a relative few €'s. We treat our Vicarious Publishing (
https://www.vicariousbooks.co.uk/) books "all the Aires of France" (North & South) as invaluable bibles, they also do similar books for Germany, Holland etc. etc.
As an indication of how tight we have become, and OK it was only in France, but our 5 week touring holiday around France last year saw us spend less than €40 on site & water charges for the entire trip, and yet that was stopping on small and mostly well cared for sites.
I hope you don't mind me giving you a couple of words of warning Darren?
It is so easy to burden yourself with a rapidly pocket emptying and generally physically and mentally exhausting holiday by sitting at home planning an extensive touring holiday, the reason being that on a map the mileages don't look all that great, but when it comes to the crunch the moving on almost every single day an additional 1 to 200 miles does become more than somewhat of a bind............ I know because like a fool I have done it so many times in the past, these days over in France we generally only move on about 40 to 50 miles each move!!
Good luck though, your holiday dos sound exciting.
Phil