Steve,
Although I don't do crossword puzzles as a past time, I consider them very good indeed from a language perspective just to get one thinking and to increase one's vocabulary not fluency IMO. Even the basic skill level to an increased level of difficulty forces one to think and even more so in another language. I was not aware that
El País had a crucigrama page however, I have seen them in other Spanish newspapers that I read occasionally. Here are two:
EL COLOMBIANO | PORTADA
Look on the left hand side, go to the section
Entretenimiento and you will find the daily crossword. If the link is down try it again later.
Listín Diario Digital - El Dinero
Listín Diario also has a daily crossword in the
El Dinero section. Go to the bottom right hand side of page and you will see juegos&crucigramas.
It's worth trying crossword puzzles from other newspapers as an alternative.
-LDG.