Parque Nacional Los Quetzales
The quetzal is more abundant from October to January but anyway you can see it all year round. Very early is best before too many people disturb the shy quetzal.
In the San Gerardo de Dota Valley and the Los Quetzales National Park birding is outstanding. The Quetzal is one of the most beautiful birds on earth. Enjoy a walk through the amazing cloud forest. You might have a guided walk. Try to start as early as possible. Be prepared it might be cold in the night. Have an additional sleeping bag and perhaps a hottie.