Wow, this is a tough problem to have...if you've tried being frank and downright blunt with him and he still does not get it, then I would suggest marriage counseling. Finances are a huge reason why couples get divorced, as well as not being able to communicate with each other. Hopefully some type of counseling will help with the communication issues, as well as getting the root of why he feels justified in spending like he does.
I can understand why, if he does get deployed overseas, he might feel the need to splurge on a vacation some - maybe he feels he needs to leave his kids with good memories of a special time together in case he is suddenly not around some day. And that is not necessarily a bad thing. On the other hand, is there any money saved for the future? For college for the kids? For retirement? Do you both have life insurance policies? If those things are covered and he were a little more willing to tighten the belt in other areas, a nice vacation would be justified.
Personally, you getting a job might not be a bad idea. It will be money that you earn and unless he seriously expects you to just turn it all over to him (and I hope to God he doesn't), you can put it aside in savings for whatever you might need it for. However, both you and he need to consider that if you are working, someone has to watch the kids and that someone might need to be paid (unless it is a family member willing to do it for free). So whatever money you earn could get eaten up by that. However, personally, I don't think it is always a good idea for a woman to allow the husband to make all the money and have total control over it, especially if the husband can't be responsible about it. Women sometimes need to take responsibility for their financial lives too and not always depend on the husband, if he can't be trusted to do the right thing. What would happen if he died?
I'm sorry you are going through with this...my hubby sucks with money too, but at least I have a job that earns enough to cover our bills and then some. We are having some similar issues and I am trying to figure out a solution too, but if something does not change, I might have to haul his butt to see a marriage counselor myself. I think a lot of his issues stem from growing up poor, never enough money for anything, and now he feels "entitled" to the nicer things in life without realizing that our savings is not an ATM.
Maybe see what other responses you get, and then maybe print all this off and show it to him...and sit down and have him watch Suzie Orman with you.