Kay and I love our vista views as well, even though we've never actually been camping with our trailer yet. They were one of the things we were looking for in a vintage AS. Yes, they can leak. But then, any of the 30+ year old windows can leak on one of these trailers. And all of our did...
Most of them, like the front wing windows, were double pane when installed by airstream. At some point, but I'm not sure what year this happened, airstream switched over to single pane. In our trailer, all 3 vista views and the two wing windows used to be double paned, but prior to us buying her last year, some PO had removed one of the panes to make them all single paned. I believe, based on what I've read here in the forums, that the inside pane was a plastic material, and it was extremely prone to fogging up so you couldn't see out of the window. When we got our trailer, 2 of the vista views leaked terribly. Both of these had been replaced at some point. The one original one did not, and still does not leak. Repairing them really wasn't so bad. If interested, you can see how I went about the repairs here (post 16):