We took the Coral Princess (Oct 13-23, 2006) 10-night voyage to the Panama Canal last year. This voyage was a partial-transit through the canal. We did not take any excursions.
We arrived at the canal just before 7am. It took about 90 minutes for the Coral Princess to pass through the three locks and enter Gatun Lake. (It seems each lock takes 30 minutes). We anchored in the lake until about 4pm. It was almost 100 degrees and sunny. Then we returned through the same three locks and docked at Colon, Panama until about 7pm.
At dinner, many of our tablemates had taken excursions. One couple said they wouldn't do it again. The trip was hot and uncomfortable (they may have been referring to the "nightmarish bumpy ride"). They said the best view was from "our own balcony".
I did not post this to discourage you from taking any excursions. My husband and I felt fully satisfied with our Panama Canal experience.
Maybe next time we will complete the canal trip and exit the Pacific side.
Carnival Liberty February 10, 2008
I have recently posted photos from this trip on the Photo Gallery