We did 14-day Infinity Trans-Canal December 8, 2002 and December 7, 2003. We specifically booked these cruises for the number of sea days. We were okay with the itinerary the first time, however, the second time, we rarely bothered to disembark the ship. The only port stop we had planned to disembark was Costa Rica but this port was skipped on the 12/03 cruise due to a medical emergency. (Fine with us as each cabin was compensated.)
While we were okay with both PC cruises we especially enjoyed being on-board Infinity again(our 3rd time on Infinity as we sailed her during her inaugeral year to Hawaii)
I can't say that this itinerary was among our favorites but I'd probably cruise anywhere as long it was with "X" and on an "M" class ship.
Everyone who enjoys cruising should do a Trans-Canal - once.