When we moved to Europe two years ago, we took the Queen Elizabeth II. It was more economical than airfare for our family (six children at the time) and we thought it would be better to arrive at our new home without jet lag and all the stress that goes with a long flight and small children. It was an incredible experience, and we loved every minute. I would highly recommend it.
Coming back from Europe, we flew (now with seven children) and I still haven't completely recovered from that experience. (The kids were great, the airline had several delays, among other issues.)