I think Disney’s basic original plan was fine. They just botched the execution. If I was in charge in 2012, I’d probably try to pull off the same plan, i.e. Episodes 7, 8, and 9, with stand-alone stories in-between. (An episodic streaming series wasn’t really an option back in 2012.)
I’d definitely try to execute the Sequel Trilogy a lot better and with significantly more planning, along with longer periods between movie releases.
I’d also tweak the overall plot of the Sequels significantly. I think the actual Sequel Trilogy had precisely 3 interesting concepts, all of which were mostly squandered. These are: (1) a Storm Trooper main character, (2) a female Jedi main character from a junkyard planet, and (3) the Knights of Ren as some kind of cool new order of non-Sith Dark Side users led by Han/Leia’s son.
My ideal Sequel Trilogy would incorporate these concepts, and scrap mostly everything else. I’d replace Rey with her earlier incarnation named “Kira”, who had a much rougher, street-smart personality, which I think better fits someone who grew up on a junkyard planet. I’d also start off the first movie showing a “day in the life” of both Kira AND Finn, unlike the actual Episode 7 which only showed us Rey’s daily routine. I would want to see Finn going through a day in his life as a Stormtrooper, eating in the mess hall of a Star Destroyer, going to his quarters, etc.
In terms of the larger story, there would be no attempt to “soft reboot” Episode IV, i.e. no political reset back to the Rebels vs. Empire status quo of A New Hope. The story would take place approx. 30 years after ROTJ, like in the real Sequel Trilogy, but the Galaxy would be divided between a dominant New Republic and various Imperial factions, like in the old EU. I’d use the original Thrawn trilogy as a general plot template, but change many details to incorporate the new characters. The basic outline would be Thrawn going from an underdog fighting the New Republic in Episode 7, then shifting the balance of power by the end of Episode 8 (maybe by acquiring something like the Katana fleet), and finally have Episode 9 revolve around the New Republic’s attempt to retake Coruscant. Kira would train with Luke to become a Jedi, Kylo and the Knights of Ren would replace the role of Joorus C’boath, and Finn would have a much more prominent arc, culminating in some incarnation of the Stormtrooper rebellion idea from the Duel of the Fates script. Han would die in Episode 8, but I’d keep Luke alive and end Episode 9 with Leia becoming Chancellor of the New Republic.*
* Since it’s all hypothetical, I’ll just assume Carrie Fisher is still with us in this alternate reality. And now I’m sad…