My two cents, who knows maybe I will even get some change!😉  I am writing this as though you would visit Agua Clara Locks first, although they may reverse the order to provide the best opportunity to view ships in the Locks.  Honestly I don't think the bus ride is all that torturous with a decent road for the most part and nice scenery.  From Agua Clara Locks across the Isthmus will run you a little over an hour and from the Pacific side back to Colon closer to an hour.  In Celebrity's overview