T, there are basically two primary AOE's in Costa Rica: MROC (San Jose) and MRLB (Liberia).
I have operated numerous times into MROC but not into MRLB. As others will tell you, MRLB is likely much more convenient to the pacific side. From time to time MRLB will run into Jet-A supply problems, so that is something to check on if you plan on going there.
I have used a handler when operating down there as is just makes everything easier in getting the pax off and back on the airport. As I recall, both airports need 24 hrs. notice of arrival. Go with Airrouting or Universal and you'll not overlook any details.
If you use MROC the Marriott San Jose is the place to stay. Wonderful property just south of the airport. It's about a 20 min. cab ride to down town. And you'll owe it to yourself to check out the Blue Marlin Bar at the Hotel Delray.
ADS Ground handling has provided excellent service and will take care of getting you into and out of the country at either airport. <www.adsgroundhandling.com> Dellmark Muir is very professional.
enjoy.