We have a 6 hour layover in Costa Rica, a short stop in Lima, possibly about an hour if I remember correctly, and then directly to BA.
On our flights to Chile, we had the same layover in Costa Rica and left the airport for a few hours. We took a walk through a park across the highway from the airport and enjoyed watching the kids play. This time we may hail a cab and "go somewhere" as 2 of the women I'm traveling with this time have never been in Costa Rica.