Lots of good advice above.
One could write a whole lot of "operational tips" on foreign flying.
#1 top tip is: always get Avgas immediately after landing. If the van or bus turns up to take you away (usually happens fast) refuse to board it until avgas turns up. This avoids undefined waiting prior to departure.
#2 Contact the airport first (phone or fax) to check avags availability and acceptable payment methods. Some take weird combinations only e.g. only Mastercard. Some take only cash!
#3 Contact the airport first re PPR and any special requirements. Best done by fax, and say on it it is OK to hand write the reply on the fax and fax it back (not many people can or want to type up faxes these days).
#4 Try to be independent when it comes to getting weather and filing flight plans, GAR forms, etc. This means having mobile internet (a laptop with GPRS/3G). Flight plans are filed using
Homebriefing. This removes a massive chunk of hassle from flying distances. Airports vary hugely in their facilities to pilots - Switzerland is the top with every thing laid on even at the smallest tarmac strip, the UK is pretty variable, and Spain is somewhere in the 3rd world. If you don't have mobile data, you can turn up at the airport at 9am and by 12:00 you are still hanging around waiting to file the flight plan.
#5 Try to pick every stop to be interesting in its own right, so if you get stuck there it doesn't really matter. The exception to this is if doing a long multi leg trip in very good stable weather, but it can get very stressful because it is so easy to get held up waiting for fuel etc. And pre-filed multiple VFR flight plans are a risky proposition; more often than not one of them will get lost and you don't discover this until you have started up and call up for departure clearance... Once I filed four all 3-4 days in advance and 3 of them vanished.
#6 Allocate tasks which carry a risk of delay to parts of the trip where you have time to waste. Getting avgas after landing is one example.
#7 Plan ahead your luggage. Split it into two parts: stuff that stays in the plane, and stuff that you take to the hotel.
#8 Phone the airport well before departure to check they have your flight plan (if you filed it via the internet).
#9 Plan most flights to depart in the morning. Pretty obvious really - gives you the most time to play, as well as usually the best weather.
La Axarquia (LEAX) is a nice sleepy destination near Malaga, but isn't international so one has to land somewhere within Schengen first, but in a PA28 one will have little choice about that anyway.
Spain is a great value for flying. The scenery is totally spectacular, weather is normally good, airspace is easy enough for VFR (though I sometimes had to fly at say FL105 to get above some restricted area, when the other option was to bank on getting a transit through some Class D, and I always preferred to take the guaranteed option). And if you say the word "commercial" 3 times when getting avgas, you can sometimes get half price avgas
Nowadays I go IFR (airways) for all foreign trips but France/Spain are so casual about things that one ends up flying more or less the same route! I am going to visit Granada this year, and a couple of other places in the north. The TB20 can do Granada in one leg.