...I've got my ideas...I feel like I need to so something just as awesome to bring it all to a close, but before I launch into anything, how do other folks wrap up their epic campaigns (or would want to, but it got derailed)? Do you even do an epilogue?
I have a few Homebrew Campaigns. Each has an epilogue.
The first ends in a little bit of a Railroad as the PCs discover that something was underway a thousand years before they started adventuring that needs to be handled. While there are many solutions to the problem, the one that every group that has run it has utilized ends up with a PC needing to sacrifice themselves by being on the other side of a portal that leads to a very bad place. As an epilogue, I run a '5 years later' adventure for the PCs where they try to save their lost ally when they discover a brief window in which it might be possible. The person with the lost PC (and and player that had their PC be lost in the final adventure) get to play NPCs or make a one shot PC. So far, every group has failed to save their lost ally. However, the epilogue also features a return of elements from the campaign that I get to wrap up.
The second is a Megadungeon that focuses on a ruined mansion on an island along an abandoned trade route. The Megadungeon takes the PCs to the Shadowfell (and specifically a Ravenloft domain), Feywild, and Ethereal (which in my setting is a transitive plane between the Far Realms and the Prime) in "reflections" of the manor, the dungeon and the surrounding environs. Then they get into extraplanar antics to solve the mysteries of the Megadungeon. In the end the PCs can either destroy the place, claim it, or send it elsewhere. Whichever they choose, I have an epilogue that I run based upon their choice that introduces elements that sets up campaign three...
Campaign three is a war campaign. If the PCs elect to play in this campaign, they are told their PCs will be pressed into military service, so the game does not work if their PCs are unwilling to fight to protect their families and friends ... although they don't have to be happy about being pressed into service, they can't run from the obligation. They go from refugees to soldiers to a strike force, to leaders, to generals to the decision making body for the war effort ... and the future of a large section of my campaign world hangs in the balance. Underlying the entire campaign are the legends about two historical figures - the first Archmage and the world's most talented 'Artificer'. The two times it ran, the PCs made the same ultimate choice - and regretted their choice (although I feel like the regret is a "grass is always greener" regret. Regardless, the epilogue moves the world ahead a decade and features the resolution of a prophecy that comes from the 'Artificer' - one of several that the PCs can/should address during the campaign.
I have others, but there was no appreciable epilogue ever run for them.