As for my experience, i would choose deck 7.....not too high, not too low. i don't like being too low because it is far away from the amenities. however, what does influence my decision is where on the ship the room is. we always always get rooms in the center of the ship, near the promenade due to our motion sickness. the best place for those who experience motion sickness is middle and bottom of the ship - where you feel the least movement (hint....this is why the ice rink is located where it is on all of the rccl fleet). we find, however that being at the bottom or the top doesn't really affect that much for us. hope that helps.