Dont let anybody scare you into seasickness. It rarely happens and unless you are especially prone to motion discomfort then dont worry about it. People sometimes freak themselves out about it and think they will get sick but a majority of the time its fine. Large ships are built with stability in mind and as long as you have decent weather then all will be well.. enjoy and forget about the what ifs...
2008-Valor and Glory
2009-Spirit and Splendor
2010-Freedom of the Seas and Mariner of the Seas
2012-Allure of the Seas and Navigator of the Seas