One of the things I liked in the early novels was the sense of history. The prologue of the Star Wars novelization talking about the slide into tyranny, SotME showing us a neglected Imperial mining planet and how non-humans were regarded and treated, Bran Daley's Han Solo books giving us a broad swath of everything from the Corporate Sector to Z-95s to Han's military career to how most people were just trying to keep food on the table regardless of who was in charge...
I feel like the PT spent way too much time at the center of power, and the ST none at all. There was stuff in the ancillary material surrounding the PT that bothered me, like no standing military and George having no sense of scale. We absolutely should have seen those Z-95s all the way from the beginning. They're the F-4s of the GFFA -- semi-obsolete holdovers from an earlier era that are still viable enough for a peacetime military and various planetary defense forces to use them. There was stuff in the EU that worked great about how the early ones had bubble canopies, variable-geometry swing wings, and triple blasters in each wing... And the design gradually evolved until, during the Clone Wars and after, late-model Z-95s were the direct inspiration for the T-65 X-Wing. Some Z-95s were even fitted with splitting S-foils for improved wingtip cannon coverage. Then there's the whole Y-Wing evolution that's been hinted at since the first film.
If George had trusted first instincts and kept the Obi-Wan films at six episodes, maybe we would have gotten to see more of the galaxy at large -- the Alderaanian Guard, the Corellian Defense Force, the Rarefied Air Cavalry, the Tierfon Yellow Aces, the Republic Navy shifting from peacetime complacency to the shocked reaction to finding themselves in war that eased the slide into militarism and authoritarianism. Boba Fett's better backstory from the comics and the impact that could have had on the galactic Risk gameboard*.
[*Slave I was originally conceived of by the designers and builders as one of at least a score of interdiction craft, with crews of three. There was conflicting material around the time of Empire as to the nature of the people who wore the armor Boba Fett opted for. One said they were a race of evil warriors defeated by the Jedi during the Clone Wars. David Michelini, over at Marvel, spun that out into a cadre of 212 supercommandos charged with the ultimate defense of the Mandalore system from the Empire (since we didn't know who was involved in the Clone Wars. Since history is written by the victors, naturally they were painted as villains. Only three survived, one ship. Boba abandoned his people to become a bounty hunter as the Empire occupied Mandalore. The other two stayed on to fight a guerrilla war against the invaders. I much prefer that to what we got.]