There is no need to go to Coronado to arrange a tour.....they do not have a storefront. Contact them through e-mail on their website or call them once in Panama:
Neil and Denise are very friendly expats from Canada who live here now. They only thing I would emphasize to them is that you want someone who is knowledgeable about Panama and its history, etc. for your tour guide. I know they are very busy and they hire other expats to take visitors on tour and I remember one complaining his tour guide spoke English but was new to Panama himself and did not know much about the history of Panama.