Le Castellet is the best bet, with a few provisos...
If the weather goes iffy, getting into le Castellet will be a challenge. From memory, non-precision onto one end, circling onto the other. We determined it was Cat B with a long briefing carefully written beforehand, but there might be arguments it should be Cat C...
Do get the aircraft straight into the hangar - if it's parked outside it will get covered in dust and some sort of sticky sap from the pine forests, and there are no washing facilities.
HOTAC around le Castellet can be a problem if you want some life in it. Best bet might be to have a hire car and only stay near the airport if you've an early departure.
Catering will be a big problem - no caterers there or nearby.
Others are right in saying Barcelona can be a terrible place to go in a biz-jet. Sometimes I've been there we have had great service, in and out, though with miles of taxiiing. Others, we've been stuck for what seemed like a lifetime, waiting for handlers, fuel, etc...