I'd go online and do comparison sites for the best deals. And they are usually a minibus ride away from the airport, which is a minor inconvenience but not too much of a ballache. Did this at Christmas and got a Fiat 500 for crazy cheap for the week.
Not quite on topic, but anyone recommend a specific car hire at Palma airport?
Hate hiring cars, always assume I'm going to get rinsed for something.