D.,
I believe I had responded to you about your 9 year old daughter a few weeks back. So, my advice will be in conection with the concern you had then.
I would really try to work out going - BUT only if your 9 year old has earned it. Maybe you can get your hubby on board for that if her behavior has improved - and something like this would surely show her that special time with her is important too.
As for coverage for the other kids - maybe you can go to your church to see what they can help with. They might even have someone whom you know be willing to baby sit just to help.
If you can't get your hubby on board, or you can't find someone locally to help out with the sitting for the other 2 or if your daughter hasn't 'earned' the trip, I would see if where you won it from has a 2nd place prize that you could switch with. There is some advise on selling the tickets on ebay or craigslist - but you'll need to find out from where you won them if you can do that.
Good luck and let us know!