I was scheduled on a delta flight from ATL-SJO a little while back. My flight to ATL was canceled, and I was re-routed through JFK, then to SJO on Lacsa on the 1am flight. Much to my surprise, it wasn't bad at all. I even ate the meal and enjoyed it. I was so exhausted I slept most of the flight, but even in a middle seat in coach it wasn't that bad.

Enjoy your flight, and enjoy Costa Rica. It's a great country.