Warning; rambling and poorly organized thoughts below. Lots of spoilers (duh!).
Top changes I would make to The Last Jedi (and that I honestly think could have been made keeping most of the key plot points and footage). End result would have been a passable movie.
Lightsaber toss is changed into Luke handing it back to Rey and walking away. Luke is really just testing Rey's patience as Yoda originally did to Luke.
Leia dies in space sparking Luke to cut the Yoda-crazy-act and train Rey. Bonus points if Luke is lead to believe Kylo Ren pulled the trigger (even though he didn't).
Rose never happens.
Canto Bight never happens.
Dreadnought and bombers in space never happens.
Hacker guy never happens.
Slowest space chase in history never happens.
Super-super Snoke star destroyer never happens. How about the First Order shows a bit of set back from having lost a planet-sized base!
Yoda never happens.
Frog people never happens.
Universe spanning mind link never happens.
Luke flashbacks to trying-to-kill Kylo never happens.
Resistance escapes directly to the salt planet and activate the defenses.
Rey/Luke sensing the impending doom of The First Order having the remnants of the Resistance trapped on the salt planet fly off to save the day. However, due to being cut short on time to train together they have a disagreement on how to proceed.
As they arrive at the planet Rey jettisons herself from the Millennium Falcon.
Snoke sensing Rey's arrival tells Kylo Ren to bring her to him.
Luke and Chewie are forced to escape to the planet and meet up with the resistance.
Snoke pits Kylo and Rey against each other. First, he trigger's Kylo's teeny-angst by planting false lies about Rey's parentage and how Rey is his better. Second, he trigger's Rey's emotion by telling her that her parent's were nobodies and that she is just a pawn to the force filling a vacuum.
Rey and Kylo have an epic fight before realizing that Snoke is playing them. They turn on Snoke to kill him but have to go through the red dudes to get it done. Snoke is greatly amused by the fight assuming he can kill the weaker of the two and keep the other.
After Rey and Kylo finish the red dudes Snoke utters a bad ass one liner like "good, use your anger". Then Kylo realizing he is forever limited by Snoke (the same as he was limited by the weakness that was his father, Han) turns and kills Snoke. Before Snoke goes down he utters "if you strike me down I will become stronger than you ever could know" setting him up to return in the next movie. Kylo slices Snoke's head off.
Rey can't convince Kylo of her viewpoint and vice versa Kylo can't convince Rey of his. Kylo traps Rey and finds out Luke is on the planet. In a rage he takes an invasion force to get Luke.
Rey escapes and heads to the planet.
Luke fearing that Rey has been turned to the dark side fights to the death on the planet surface. Kylo and Luke have the most amazing lightsaber duel all the while Kylo is taunting him about Rey. Kylo takes a wicked face hit forcing him to forever keep his mask on in future movies.
The Resistance hope-o-meter goes bankrupt as Luke falls on the battlefield and they escape into the tunnels.
Surprise, Rey is OK and saves the day. The Resistance's hope-o-meter is full again.
Ending scene is Kylo donning his mask and going "Noooooooooooooooooooo!!!!" as the Millennium Falcon zips into hyperspace.
Where are Finn and Poe during this movie? Keeping the bromance going and working to keep the remnants of the Resistance from imploding under the doom and gloom.
Phasma? I actually sort-of-like Phasma being a running meme in each new Star Wars movie. A slow roll of her trying to squash out the "bug" that is Finn would be epic.