These are largely personal choices and things that you pick up as the need arises but I thought you might find this small personal selection useful as a starting point.

For UK use we've always tried to use maps that show the national grid since the UK sites listed by CC & CCC always have a grid reference which is extremely useful when trying to locate say a farm site.  These are increasingly difficult to find.  Of course you do have to remember which trio of grid reference numbers go which way but I expect you all know the old mnemonic 'along the hall and up the stairs' to remind you to go across the page first and then up.

In Europe the Michelin maps are extremely useful as is their on-line route planner.  I just wish they did their 1:200,000 scale over all of western Europe instead of just France!  By the way when looking for maps like these don't forget Amazon as well as Stanfords and your local Waterstones of course.

As birdwatchers we're particularly keen on the 'Where to Watch ..' series from Helm and as Francophiles we wouldn't be without 'Le Guide Officiel Etapes Touristiques Camping-Car [year]', which lists nearly 5000 Aires de Services and possibly 'Le Guide Officiel Camping Caravanning [year]' for nearly 11,000 campsites!  These are available from French hypermarkets early in the season and sometimes in the UK but you can order them on the web from www.alplage.com and www.amazon.fr (.fr note!).  See also the France Passion info on the European info page.

The official tourist websites for each country can be useful too but don't carry anything like the number of camp sites that the best guides do.  A major failing if you like the smaller more informal sites as we do.

I'm interested to know if anyone has similar tips for say Spain and Italy?