We will be taking our first cruise (to Alaska). My sister-in-law is extremely vulnerable to motion sickness and is concerned about what cabin area she should get to miimize the effects of motion sickness. She is leaning toward a higher deck in the balcony section as she believes this will do the trick. As a former navy seaman I believe she would do best to try to stay lower and towards the middle of the ship to minimize motion. Please offer thoughts based on experiences with these size liners. We will be on the Coral Princess.