Spent a month flying in the Gibraltar / south west spanish airspace, Most of Spain is pretty free of restriction.
South Spain isn't quite as nice, getting to Gib is a pain as there is a restricted zone right the way across the coast about 40 miles wide and up to FL300.
To the south west there is a USAF base ROTA that controls the coast and the waters up to flight level 280 for the most part. This kills off most of the coast for about 70 miles, spains restricted/danger areas arnt like the ones in the uk, they are no go.
This is the same with any non civil bases, at best you may be able to transit the airspace but it's unusual.
North of Gibraltar you have another military base called Moron, other than the ATZ being restricted ur ok as they restrict from FL150.
Above Moran to the north west you have Sevilla, they are busy but are incredibly helpful and accommodating to GA. This is a big big plus point in Spain, there is never any 'dam ga planes' if your new to an airport they will talk you in, tell you where to go to pay ur landing fee, even offer a follow me if you want
The trick to getting through the maze is the cut via La Juliana, it's a restricted zone but it's only up to 1000 feet, you can then cut direct, or go around / over.
I would recommend Jerez if you need a stop, there is a club 'Real Aeroclub Jerz' on the GA apron, access airside, you may be able to pre-arrange to go direct to them, if not then ops will want to bring you back to the terminal and there is naf all there, esp lacking in pre-flight. You must have a flight plan for all legs, if not ATC will not let you taxi.
Must be in 30 mins before flight and if your not ready to roll within 30 mins it gets cancelled automatically.
Lastly all spanish airports have entry exit points more often called echo whisky sierra and November (inline with NSEW) you must know these if your coming in VFR. Enty is 1000amsl and 2000 outbound amsl (but this changes per airport).
Lots of airports also have left and right circuits active at the same time.
Tho in general flying in Spain is so much more relaxed and easy going than UK, the scenery is amazing, flying down Gibraltar and the Morocco coast is out of this world !
Ian