Since you will be in the area, definitely visit palo verde. You can see so many herps its not funny.. think neotropical rattlesnakes, caimen, crocs, oh so many frogs. Seriously consider the amphibian consevation center in Guyacon though. I swear it is well worth it (like glassfrogs?).
Good lick and I hope you have a great trip. Also make sure you have an excellent light. A hand held spotlight with battery pack is ideal.