Royal Caribbean offer fantastic ships. The serenade of the seas is beautiful and the whole package RCCL provides is Great! I've cruised western caribbean it's faB.
We did this trip in April this year (07)on Serenade and had a wonderful time. It's certainly worth getting up early in the morning to 'bag a good viewing space' for the 1st locks (Gatun) and also to be up on the top deck as you go under the Golden Gate Bridge.
Take clothes for three formal nights!
Only (slight negative comments) - we felt some of the excursions were 'filler-ins rather than highlights (although driving a 4x4 at Cabo San Lucas was a definite high)and the ship did 'rock'n'roll rather on the way from Cabo to San Francisco. San Francisco highlights tour was good - when we eventually managed to disembark which was the most chaotic, disorganised event of all cruises we have ever been on! Oh! and take a jumper for San F - all the fleece jackets in the ship store sold out as it got pretty chilly.
ENJOY - we did.