There are many car hire companies and we list some for each of the airports. For all the airports we recomend Rhino Car Hire or for Malaga airport we recomend Compare Car Hire.
The biggest issue is making sure the whole car is insured. Very often the under-carriage is not insured, or in some cases the interior is not covered or indeed the roof. Some of the roads to the beaches are tracks so having no under-carriage insurance could leave you with an unpleasant and unexpected holiday bill. We recomend you consider TDW - total damage waiver
Jerez de la Frontera Airport
Seville Airport