Things that would be interesting to see -
A somewhat fleshed out scenario of an alternate Anglo-America that either dodges chattel slavery entirely, or ends it decisively early, after a relatively brief period of no more than a century or century and half.....but that has the following kicker: along the way the society picks up some *other* quite ugly dystopian institutional flaw making most readers glad we don't have to live there.
One could re-play the same thing extending it to Ibero-America, or Euro-America writ large, to extend the affect to Brazil, Caribbean, and the Spanish Main.
Another thing that would be interesting to see -
A somewhat fleshed out timeline where the American Revolution is headed off, not by the British Empire conceding everything to the colonies, or something like the Galloway Plan, or coming up with latter-day self-governing Dominion systems early, but instead where Britain:
a) Gets to impose a benign central taxation administration from the beginning, or gradually over a set of decades from some point in the early 1700s or in the 1600s, and gets the Colonists used to the idea of the 'virtual representation' idea. Britain treads on the snake by boiling it slowly! Not leaving the 13 Colonies alone in the pantry for 150 years and then showing it the tax collection boiling pot like OTL.
b) Britain never faces anything quite like OTL's American Revolution because elites of different colonies and regions of the seaboard never discover the commonality of common grievances and gain the confidence that they would have the support of their whole communities, much less, all the other colonies, in measures like the anti-British boycott, Stamp Act Congress, Continental Congress, forming a pseudo government and army, rebelling and ultimately declaring independence. All the seaboard colonies elites getting themselves on a pretty similar page, without a similarly scaled local opposition was a quite remarkable thing - the colonies being divided and all on different pages is truly an under-examined scenario.