Never EVER threaten something that you're not prepared to carry out OP! That to me is one of the first rules of parenting, as when you say something your child/children need to know that you mean it.
It does sound like you've been letting them get away with an awful lot of bad behaviour, do you and your husband agree on how they should be brought up, or is one strict parent, and the other lenient, so the boys can play you off against each other? If this is the case, then you really need to have an adult conversation, away from the children, about how you are planning on going forward as parents, and again, stick to what you agree. For example, if you say 'no' to something, and the child goes to Dad and asks again, Dad must say 'have you asked Mum, and if so, what did she say', then if Mum said 'no', then Dad says 'no' too, no matter whether he actually agrees or not, as otherwise you just undermine each other. You then talk after the kids have gone to bed, about any situations which have occurred that you didn't agree upon, and decide what to do about that situation if it arises again. To coin a phrase, you must always be singing from the same hymn sheet.
If you ask them to do something, then make them do it, don't just keep telling them to do it, and then end up doing it yourself 'because it's easier'! That is lazy parenting, and tells your kids that they only have to ignore you, and you'll do it yourself anyway.
I would suggest that you and your partner decide whether or not you want to go ahead with the weekend, and then tell the boys. However, if you decide to go, but then they're naughty, and you say 'if you don't behave we won't go away for the weekend', then that's it, if they're naughty again, you must NOT GO.