Suggestions please, France, Millau to Calais

Hi, hoping all you seasoned France travellers out there can offer us some suggestions. I am planning our return holiday tour from Murcia at the end of May to mid-June and trying to work out how many days to allow for some sightseeing on the way home. We shall leave Murcia and currently plan to stop off at the following locations using the ACSI sites, staying for 2 nights at each, with a stop close to the Calais ferry to allow for any problems and giving flexibility to stay a day or so longer en route. Benicassim, Sant Feliu de Guixols, Argeles sur Mer, Millau then not sure after that.

If anyone can suggest a place to stay, I was thinking of heading via Clermont Ferrand, Orleans, Rouen and then Calais and am probably looking for 3 more sites after Millau with a final one being reasonably close to Calais. We like to be able to walk or cycle to the town/village for shops and sightsee but are also happy to view the local scenery.

Some of the places, like Millau & Argeles, have an abundance of sites to choose from so if anyone knows of one that is better suited to a large motorhome than another please feel free to suggest one.

I know there is a wealth of experience out there so I will be grateful for a little help to just put the finishing touches to where we already want to go and my lack of knowledge of France is a disadvantage. I am sure wherever we stop will be great.

Regards, Roy