Skateboarding should be your last resort when visiting Europe, there's so much to see. Honestly don't even bring your board, Spain/ France are more fun without skateboarding. I'm a skate addict so you know it's coming from the heart
If you have to bring your board, check out Malaga. Tons of untouched spots noone else will see. Spain is great they have the fastest train in the world and France is right next door.
You will be treated like shit as an American, so be prepared for that.. Don't pretend to be Canadian I've seen fools try and pull that, not cool.