Summer Trip

I am planning my summer Panama trip right now. I want to hit the usual spots, El Valle de Antón, El Decamerón and of course, my dad's place, Keruasa. This time though I would like to see some other places that I haven't been to at all or in a long time. I am thinking of possibly going to Coiba, Darien and Gamboa. What would REALLY be awesome is to go to one of the Smithsonian Institute's research-education centers such as Barro Colorado, Galeta, or Culebra.

Question:
Have you been to any of these places? What do you recommend?