Location is all about preference if your prone to seasick pick midship. I usually get the highest level/near the stairs, be on the lookout for being near the laundry room/bar as they can be loud even at night. I've heard the deck below lido is always loud as well as you can hear the deck music/parties going on especially if they hold a midnight buffet and your trying to sleep. Balcony is great if you plan to eat room service breakfast since you get the view, though on a short trip I'd skip it.