If I have up to 3 days to spend in Panama City on a layover to Ecuador, what must I see besides the canal that I can't see in Ecuador?

I am spending about 12 days in Ecuador and seeing Galapagos, Quito, the Amazon, a volcano and rainforests. I have a layover in Panama City and have the option of extending that layover to 1-3 days. Other than the Panama canal, I'm not sure what I should try to see in PC that I won't already be seeing in Ecuador. Have any thoughts on what I should go see in PC that is unlike anything I'll see on my Ecuador trip?

Thank you!!

Asked by John via Travellr.com