Sorry OP, I know you’ve been busy but I think you’ve been asked, for 100% clarification, whether this is just your OH who would be going or you and the children too ? Posters seem to be coming from both points of view.
You, as a couple, are being pressurised into either just DH, or both of you and children, into giving up a week of work leave for BIL’s 40th birthday bash (heaven only knows what he and the rest of the family will demand for his 50th….).
If the idea is that only DH goes, that’s a week ‘taken’ from you and your children of family time whether you would spend it ‘on holiday’ or just spending time together at home.
If the idea is that it’s families holiday then what are the expectations of a week’s worth of entertainment/trips for the adults and children? There’s not a great deal in LV for children so most experiences would be expensive. If it’s a ‘lad’s jaunt’ then, again what are the expectations for a week? Boozing, prostitutes, flights over the Grand Canyon, other touristy trips, or wall to wall gambling? None of those are cheap and why would the guys want to do touristy GC trips or similar without their families?
Your in-laws seem to want to guilt your DH into taking a week of valuable holiday/leave time and borrow money you haven’t got, from them, to pay for it, then repaying them with money you don’t have spare.
Even if the in-laws fantasy money tree was giving you the money, do you and/or just your DH actually want to spend the leave and/or money for just him or you all to take this trip?
As I said, what about the ‘extras’, of trips, entertainment, gambling?
My husband and I spent two nights in LV just to say we’d been and to see the sights. The Strip was fun and we walked our legs of both evenings and we did a trip to the Grand Canyon in the full day we were there (most of LV is rather tacky during the day). We ventured into a casino and lost a pre-agreed amount of money but to be honest it was pretty grim with sticky carpets and no real atmosphere.
My advice would be to save your annual leave and money and spend it on proper family time.