Nana,

What you can do for an upgrade is to go to reception on boarding and pay 1/2 the price differential for an upgrade if available and you don't have to take it if you don't want to. I'd be wary for an upgrade where you have no choice based on the itinerary. Some cruises are more rocky and you may want to be lower and more mid ship. Or you could be on a ship where you a tendered and your new location is right near the tenders - you can hear and see them being lowered along with noise from the anchors dropping. Oh, and the infamous vibration! Beware.