I was thinking something like a 'generic' TV show special.
For the sake of argument Usagi Yojimbo will be a TV show and all the characters will be actors.
Maybe Lord Hebi in a white tuxedo as the host of the show... "Welcome to the Super #200 Issue Special of Usagi Yojimbo Spectacular!" Some words and then he would present the first special section Interviews with the Stars! They will take place at their homes, something casual. First off, Usagi's best friend Gen! Perhaps in the middle of cooking some burguers in the grill, with some family and friends in the back of the scene. He would explain how comitted he is to the role that even he was the one that requested for his horn to be cutted. That's some professionalism right there! "It's really a pleasure to work with him" will add Kitsune, "I've learned a lot with him, he is so professional and talented".
Then Jei will be interviewed, everybody in the set love him, "out of the scenes he is a really nice guy" Tomoe will say, "He even brings donuts to the 'studio' sometimes" will add some Neko Ninjas, and Usagi will say "he is always there as a friend when you are in need". He will explain what kind of vocal tuner he uses to get that macabre voice, which brand of contact lenses he uses... Something like that
The next section... Where are they now?
This is gonna be good! Here are the interviews with members of the cast that haven't appeared for many reasons. Zato Ino, Shingen, Inazuma, Koji, Yagi, etc. What did it mean to be part of Usagi Yojimbo? Did they really expect it to get to this magnitude? And what are they doing now, maybe working as extras in commercials, they left acting and became 'producers' of some episode of the series? And of course, some gossip

Do they have kids now? Are they married? Maybe some love stories that started in the studio? Were they fired because some misbehaving of their part?
The last section of the show... Blooper reel!
Lines forgotten, some comments between 'takes' of a scene, trips and falls, the mic appearing in a frame, jokes between members of the cast(like Usagi replacing Gen's katana for a 5-inch one; Gen will react "Ha... ha... Very funny guys ¬¬"), broken swords, even some 'Stan mistakes' I imagine something like Usagi fighting with some Neko Ninjas then "RYAAAA-huh? What? Where is my... Stan!! You forgot to put my wakizashi in the scabbard! Again!"(Just for the sake of funny moments, we all know that won't happen

)
Then everyone will say some words, thanking all the readers for their support, special thanks, mentions, etc.
I hope I give the right idea with my words

In my mind it played greatly
(Sorry for the not-so-good english hehe)
Now I'm really curious to see what will really happen in issue #200!