How about Port Aventura, near Barcelona.
It is a complex of three hotels, a theme park and a water park. The theme park and water park are just minutes from the hotels.
If you stay at one of the three hotels you get free entrance to the theme park EVERY DAY, and at times it stays open till midnight.
You also get one free day in the water park, and reduced prices for the other days.
My famliy have been there for the last two years (June) and stayed at the El Paso hotel for a week. My teenage children loved it.
Hotel was great, theme park is one of the best in Europe, and water park is wonderful.
It is on the edge of the town of Salou which has an amazing beach.
Here is a map of the complex.
http://www.portaventura.es/resort/descargas/ma pa_resort.jpg
Here is one of the rides, Dragon Khan
http://www.lemonpage.de/katalonien/khan.JPG
Here is a picture of Salou, the complex is in the top left, just under the writing.
http://www.fincasmaritimplaya.com/imagenes/vis ta%20salou%2001.jpg