Science is not really sure how rogue waves form, and there may be several different sets of circumstances which result in the formation of a rogue wave. One thing that is fairly common is that rogue waves are quick to form and short-lived. I am talking minutes or seconds from start to finish. It isn't like a hurricane which forms over days. Rogue waves don't roll across the ocean for hours on end.
Cruise ships have encountered rogue waves. None have been sunk. The QE2 encountered a 95 foot wave in February 1995. I've personally gone through north Atlantic storms (in the Navy) where we had hours of 40+ foot waves breaking over the bridge.
Although they are more prevalent than previously thought, rogue waves are still rare. I certainly don't think about them when going on a cruise and urge you to do the same. Modern ships are very strong and despite the outward appearance of some they are very much seaworthy. Someone on our recent voyage on the Freedom asked the Captain about rogue waves. The Captain laughed and said don't worry about it - the ship could handle it. Sure, he admitted there would be some breakage and so forth but he was quite confident the ship would not sink.