Eloping, just the two of you, when you have children from a previous relationship?

I don't see why it would be bad form. For one, they're all very young and probably wouldn't remember it as adults (save for maybe the 9-year-old). Second, kids have very short attention spans, so they probably wouldn't want to sit through the ceremony anyway. Besides, Vegas isn't really the best environment to bring children into. Just sayin'.