If you meant Liberia (NW part of Costa Rica), we were there about a year ago. No FBO, just an airline ramp, small terminal, and the handler has an office upstairs. We left the airplane on the ramp for 3 nights locked up and no one messed with it. We didn't hire any special security or anything like that. A Falcon 50 came in a day behind us and they didn't, either. Just like any other international trip, it took a while for them to fuel us the day we left, so make sure you get there with plenty of time. I recommend at least 2 hours before departure.
No special vaccinations were required, just brought the old passport.
The handler took us to and
from here. The prices are insanely cheap! It was about a 30-40 minute drive. We never left the resort, so I can't give you any info on getting around in town.
The airport closes at dark unless you request for them to stay longer, and like my profile says next to "current position", true to form the boss was late and we had to call to make sure they left the lights on for us. I forgot how much extra that cost.
We had a blast. The first thing the boss said when he got to the airport was that he wanted to buy a place there. He hasn't yet, but hopefully he does. I wouldn't mind that becoming a frequent stop. We didn't get to do the rain forest tours, but other people we talked to said they were good as well.
Have fun!