I am planning to tour spain during April-Mai (and a lot more during the following months). I got the 1:400,000 map of spain by Michelin. Though its nice for overall planning, I think it doesn't show enough little roads and villages, mostly major roads/highways.
For bike touring I think 1:250,000 is better (but takes more map if you are planning long distance as I am.
I will probably buy the detailed maps along the way