Many people don't know this, but Radio Taxi Sant Cugat will pick you or a hapless relative up from the airport and bring them safely to your home in Sant Cugat. You tell them your flight number and they will wait for you at arrivals with a little green sign. It’s cheaper, you don’t need to worry about the taxi queue and they won’t get lost in Sant Cugat.
We’ve done this at least twenty times now and have never had any problem. This also works well for coming in on the AVE, in which case they will wait for you in front of one of the hotels by the station.