I will once again tell you to blow off the airline and drive. It really is a great trip if you can schedule this to coinside with the ferry. Save the money!!!!!
The last company that I would rent a car in Costa Rica from Budget. Last year we had a miserable expericence with Budget and I will never use them again.
Contact Target Rental in San Jose. They will deliver a car to your hotel in San Jose at no cost and pick the car up anyplace that you want to meet them. Contact an individual by the name of Jorge and he will take care of you. We flew into San Jose and planned the first night at the Hampton. It was located less than a mile from the airport and it was a value hotel with a casino and restaurants right accross the parking lot.
I promise you that Target Rental will save you at least $200 and provide a clean dependable vehicle with a GPS. Last year when we rented a vehicle from Budget the tires had less rubber on them than a used condom. Sorry, but it is the truth.
We really enjoyed LaFortuna and the drive to that area from San Jose. From there we traveled to Santa Teresa and I recommend that you listen to Wefish for travel instructions She and Roadadvisor will really help you.
But again I will tell you to blow off the idea of the airplane. We did that last year but this year drove to San Jose. The ferry ride is really cool and please be certain that you have directions to get on the "new highway." It is really a beautiful drive and you will totally enjoy it. I promise.