I went on this trip in April and I am sure you will all have a really good time.
I was a little apprehensive about the flights being with Air China but it was not a problem. It was pretty well as good as airlines such as British Airways but was not as good as the best airlines that I have been on such as Singapore Airways. If you are concerned about the size of the seats I suggest you look at Seatguru and compare it to airlines you are familiar with. One thing worth mentioning is that you are not allowed to turn on your phones , even in flight mode. You could however use a tablet or Kindle. This applied to the long haul and internal flights.
The distances do look great but every time we moved from one hotel to another it was by air and getting to the cruise involved a flight and a high speed train. It was very well organised and was not a problem.
Six of us stayed at the Premier Inn the night before and it was a very good start to the holiday. We had exchanged emails (via Julia) and had dinner and breakfast together. Make sure you book the hotel opposite the correct terminal; there are other Premier inns at Gatwick.
13 of us went on the cruise and 11 of us upgraded, we thought that was well worth doing
David