The only site we stayed in Spain was Marbella Playa Camping...really nice and right on the edge of a lovely beach. In Portugal, we stayed in Turiscampo in Lagos...again a lovely site. Contact numbes can be found in the Caravan Club book but if you want to know the contact numbers, let me know and I will look them up for you.
A couple of years ago we followed the whole Iberian coast of Spain and Portugal. We started in Andorra, then Mont-roig near Tarragona, Villajoyosa near Benidorm, Granada, Ronda, Albufeira (Portugal), Cascais near Lisbon, Rio Alto near Povoa de Varzim, Santiago de Compostella (back in Spain again), Otur near Luarco, Noja near Santander, and Igueldo near San Sebastian. It was a nice trip but, unlike you, we only had 3 weeks and it was a bit of a rush.
The best campsite we have stayed in, in Spain, was El Delfin Verde, on the Costa Brava. It is a lovely site, on the beach, with everything you could possibly need onsite. It is also surrounded by beautifull local towns and villages. Hope you have a great time.