My oldest girls

So the question now is if we should take teh older two with us. I know, we thought we had settled that earlier, but it still nags at us. We have NEVER left them like this, ever. The grandparents on both sides are not the type to take one or both of the kids overnight, just because. It's tough, they want to go with us, but will be okay no matter what. The price of their tickets is quite a chunk. If they were to go with us they would return home with Brian and not stay the whole trip. We have their passports, just in case. Ugh! Anyone with experience out there? Advice is welcome, especially from those experienced in world travel/adoption travel.
We know we can handle them, but can they handle Vietnam? Would it be better on the twins if we were to have that time alone with them? Who knows. If they were to go with us, though, I think we would shorten Brian's trip just a bit...we'll need him to be back at work.
If only money weren't an issue. Then they would go with us and stay the whole time with us in a 2-bedroom 4 or 5 start resort :) We will have to decide for sure pretty soon though as we expect to get a travel date in the next couple weeks.

Dreaming, I know...