Hey Joel,
If you're doing this on the desktop you can create a third 'parent' context that includes the contexts you care about. Then set your view or filter based on this super-context. I have about a dozen of these 'super' contexts that I use for shopping/errands lists, ppl agendas, etc.
On the mobile i can't speak to iDevices thought maybe, since supposedly they can import desktop views but on Android you're pretty much SOL as the tasks don't filter up to the parent/super context. They also don't appear in child context unless they are 'active' tasks.