Where in Spain?
+1 on Komoot for Europe.
I cycled in the Costa Brava this Sept and that was not my experience, at all. I was with locals, so maybe that had something to do with it. We hit more than a few Vuelta climbs too, but it seemed like we were off the beaten path. The French Pyranees were a lot busier.
I'm going to Ripoll in the spring for more cycling with my friends, that should be cool.