It's called a vacation. Enjoy yourself. Enjoy the time with your family.
Just don't be SILLY. Silly meaning that eat what makes you happy and what you really WANT... but don't go and do silly things like eating a plate of fried chicken or a basket of french fries when you and I both know that it doesn't fit anywhere in a healthy diet.
Eat with your family. Make the best choices you can but don't go CRAZY over it. This may be a once-in-a-lifetime event with your family. Don't cloud your memories with thoughts of what you did or didn't eat or how "bad" you were.
And YES--- there is a TON of walking in DW!!! have fun!!!