As is well known Ryanair has a Catalan headquarters in Reus and Girona. All those who live near Barcelona and want to travel to any of the Ryanair destinations will surely opt for Girona. For being the one that takes more time, for its extensive offer and probably for constitude after having used it before. Not surprisingly, during 2005 a total of 1.38 million passengers circulated through Reus while in Girona they made a total of 3.53 million.
I remember a few years ago that at Girona airport parking was small and free. That changed. Right now you are billed eight euros per day parked and it is tremendously difficult to leave it just outside the airport. That increases the cost of the low-cost flight you got and in the end the difference with flying from El Prat is not so significant.
Reus airport is still under construction. It won't take much longer than driving to Girona. In just an hour and a quarter you arrive from Barcelona and the toll is cheaper than traveling to Girona.
Upon arriving at Reus airport one parks the car in one of the uncontrolled areas adjacent to the flight terminal. They are running to finish the works and surely parking is one of their priorities to fill the coffers of the airport. Fortunately, that has not yet happened.
A warning. There is very little staff at Reus airport yet. For a few hours the same employee who will check you in will take minutes later to pack your bags. That was told to me by a friend who lost the flight for 45 minutes and was sent to Girona. So if you arrive a little late it is possible that the flight is closed and you will not find anyone at check-in. So you know: punctuality is sacred.
Seize it. They will not take too long to charge you 8 or 9 euros for leaving it parked every day that you are on vacation like in Girona.
The Ryanair offer is not as generous as in Girona but the destinations it offers are not bad at all: Dublin, London-Luton and Stansted, Frankfurt, Glasgow and Liverpool. When in doubt, I would not doubt it.