C.O.
I don't know. How old is the newest addition to the family? What is he going to do for you when he gets home so YOU can have some "down" time?
Can you afford him to go? If not - then how does he think he's going to pay for it?
If you can - why can't you all go?
Why can't you go with the kids BEFORE September so you CAN go?
Instead of moping about how much you miss doing something - I would plan something else instead...it doesn't ALWAYS have to be Destin...make new memories somewhere else...
I would talk with him and tell him just how disappointed you are that he would plan a trip to Destin without you and the kids and maybe try to think of something that you can ALL do together....