Six days to go and where to head for?

A lot of people ask us if we book our campsites before we go on our trips and the answer is 'no', the main reason being that by not booking we have the freedom to stop for a few days longer at the places we are enjoying, but move on from those we might not like so much. We always travel out of the high season and find our sites using a Dutch club called ACSI, they provide you with a book of inspected sites and allow season fixed rate discount card whereby the price of the pitch is set at 14, 16 or 18 euros including electric  hookup.
We also have the ACSI app for our IPad which you can use off line including readings all the site reviews.
We have also recently started using Camping Cheque which operates a similar fixed price system for loads of sites across Europe.
We have never had a problem finding sites with vacancies so have no worries about just turning up at a site, although sometimes we do email ahead just to be on the safe side!
So these last few days we have been looking at the sites, reading the reviews and just getting an idea of where we want to go in the first few days.

Our initial ideas so far are to head from Calais to Belgium and on to Luxembourg for a few days then continue our journey into Germany and the Black Forest. We read that the Black Forest is no place for dieters with delicious meat and sausage meals followed by their famous gateaux! Sounds like a good place to start our holiday - although hopefully we will be able to burn a few calories out walking and cycling in the countryside!
I'd love to hear from any other motorhomers out there who have gone on similar trips and what their experiences are. Do you have other means of finding places to stay? 
Back soon!
Angie