Indeed a great report ! and very very nice foto's.
I too was in Costa Rica twice in the 1990's and have been in 4 of the places you were. I do understand the choices and feel like going back there
When I was there it was (for me) difficult to get the literature on what to be expected. Therefore I concentrated more on birds. But there is so much nature out there and I saw much more than I photographed (film roll) . I think you can really combine a family trip with herping in Costa Rica, it is safe and in most places you can sleep close to nice hotspots. BUT what you saw is ridiculous......
So many species and so great pictures. I think you only met your wife and kids at the airport and photoshopped them in the other pictures
I too know the guards in Cahuita. I remember staying with my wife not far from the entry pretending to be doing nothing, untill they left the guard house at about 18:00.
After that we just crossed the bridge and went in.
Is it still open as it used to be or is there a gate and they close the park in the evening?
In Monteverde I also saw more herps and birds outsine the reserve and arround Santa Helena. I think most animals there are to be found up in the canopy...
I have one daughter about to turn 16 and I think she will do less "herping" from now on. When we went to Cordoba in August for a cultural trip she asked : "OK what rare animal are we looking for here? "
Enjoy the time with your kids,
Miguel