[quote=@Retired]
To those who have expressed interest thus far, and any who come along next, what alternate worlds or concepts would you like to see? Whether it just be a character you like/think is underutilized and would like to see be the focus of a reality the group visits, or a story arc from the comics you felt didn't end properly and would want to see revisited, or something from our real-world history you think would create a unique reality had it gone a different way, etc. 

While I have dozens of alternate realities already plotted out, I am interested and open to including others suggested here.
[/quote]

I think a world that truly, utterly utilized a One Universe approach where the characters had to be drastically different and changed by one another's existence would be interesting. Imagine if Kal-El's rocket landed to Earth at a time when HYDRA was still functioning, or if Thor's hammer were found by Barry Allen instead of Donald Blake. Or if Spider-Man were created by a spider who was an avatar of The Red, making him less of an enhanced human and more of a monster in the vein of Swamp Thing. A world full of fun stuff like that, where the dynamics are completely shifted for everyone. 

Another possibility is a DC or Marvel future where the grandchildren of each hero inherit the mantles, like a giant legacy Earth in the vein of MC2. There's a ton of rife potential there if you set it far enough ahead for most of the heroes to be dead or out of action.

Another idea I had is a DC Universe where each hero is a supernatural creature. So Superman would be a horrible monstrosity from space, Batman would be a vampire, Wonder Woman would be an undead Themyiscarian witch, The Flash would be an interdimensional demon, and so on...

None of them are wildly original ideas, but I like simple concept alterations as much as I like massive universe shattering ideas.