You may want to look for an itinerary that stops in Colon, Panama to take a tour of the locks. It is neat to check the out the locks from land in addition to doing the full transit. I'd advise an independent tour operator like Robtards to visit both Gatun and Agua Clara locks.
https://www.tripadvisor.com/ShowUser..._Province.html
I took a repositioning cruise through the locks on Celebrity Infinity and was fine in one of the newer oceanview cabins added during a refurbishment. The windows are larger than normal oceanview cabin and it was nice getting out of the humidity and heat. Speaking of, Celebrity opens the crew areas at the front of the ship for end to end canal crossing (a day long affair) and it can be really hot out there and quite crowded. There are usually a few people who faint and are taken out on stretchers. An officer recommended enjoying parts of the transit from the Promenade deck where there are lounge chairs to rest and you can actually get a pretty good sense of rising and falling through the locks. The view from the back of the ship towards the locks after exiting is also nice view if it is accessible (near aft buffet area on Celebrity Millennium class).