We did the Panama Canal on Princess. Great trip but I don't suggest taking the Panama tours as there is nothing to see but Panama Canal unless you go to the pacific. I. Woke up at 4am and watched and went through the canals while the ship went through and that was amazing.
Yes, the trip this weekend seems like it will be a little chilly. Even though CoZumel is south of Florida, our weather is 50-75 right now.