I highly recommend using @everest's World Ending Game as the true finale to the campaign. In the penultimate session have the big battle and wrap up what happens in the aftermath. But then finish the campaign with the structure of WEG. You get much more interesting responses than just asking "what does your characters do afterwards", and it lets you and your players highlight things you found interesting throughout the campaign.
Plus I've found it's helpful to get an idea of what's going on in the world in the future if you're going to be playing in the same setting again.
