Spot on from EI_DVM. The 330 seems to be becoming extremely junior for FOs, with what seems like an increasing number from both seats choosing to stay on the 320. The 321s will make things very interesting indeed, if it all goes well then it could make the fleet very attractive with a mixture of Europe/North America on a 5/3 roster. Then again it might not...
As an aside I'm sure there are still some 2 night trips to Orlando and Miami, must be a nice break during our winters!