Where you said in your original post that your husband would not like it, I was thinking that I would not do it for that reason alone. I would not agree to do something above and beyond if my husband is not happy about it. It sounds like you really would like to have your family time for the holiday, too. And just because you have done this for them before, does not mean you are obligated to do it this time.
If you do decide to watch them, I agree with someone here who said to charge $1000. Tell them you have to charge big due to it being a holiday. Anyone working on a holiday should get alot more money, imo. That would definitely do the trick to find out if you are thier only resource for this vacation. Plus, if they take you up on it, at least you will be very well paid.
