you can always record a view with no windows opened. I always record a view this way and I name it [Close All]. Normally is my view number 5. Anytime I want to close all my windows I use the shortcut [Open] 5. If I got more than one page of views than I simply copy my view to view 15 25 35...., this way I never lose the shortcut I'm pretty used to.
I also thought that Pig+close, but when we someday get macros that View 0 would be more clear choice...maybe. This also reminds me that when the macros are available, it would be nice to be able to put them in view buttons.