I don't know if this is something that really appeals to you or your kids personally, but I love history. Especially here in FL, there is none. None of that sense of history all around you, the feeling that life has been going on for centuries and will continue for centuries more.
Also, I miss winter.
As I've said before, one of my big reasons for agreeing to move is the opportunity-how many people really get the chance to live in another country? If your kids hate it, they can move back-but wouldn't they love to be able to say, "Oh yes, I lived in Europe"? Even if this move was one I didn't want to make, how could I deny my daughter the experience?
It also sounds like you have more family there, I could be mistaken but I got the impression that you're not very close to your side (physically, I mean) and it might be nice to be closer to a branch of the family that you haven't been able to see as much.
Personally, I love England and can't wait to go-the decision was a real no-brainer for me.
Good luck!