I was thinking about this on my drive home from work yesterday because this is what occupies my brain sometimes. But the order of events in the Marvel MCU don't completely add up for me, and there are some things just outright missing. (Yes, I mean the Black Widow movie.) So I've decided to just go ahead and list my dream timeline to get it out of my brain and onto the Internet.
So here we go:
Ironman. Although it isn't linear, I'm ok with Ironman being first. It gives a primer to the world the rest of the heroes will eventually inhabit, plus Tony Stark is just fun.
Captain America: First Avenger. However, I would have it end happily and Bucky still alive.
Black Widow (with special appearance of Hawkeye and Agent Coulson). Basically, it's Budapest.
Captain America: The Second First Avenger? This movie would be more WWII exploits with the Howling Commandos that includes Bucky's death and Steve going into the ice at the end.
Captain America: Winter Soldier. So now Steve has taken down SHIELD it makes more sense that everyone was a bit busy to help each other out for...
Thor: The Dark World and Ironman II. I'd also love a Bucky Barnes: Winter Soldier stand alone movie, of him dealing with who he was and getting himself back before he lets himself be brought in by Steve.
Avengers: Ultron. So now everyone comes together again (including Bucky and Sam, and skipping the Bruce/Natasha relationship) and THAT leads into Ironman III where Tony is suffering from PTSD (and a shitton of guilt) and why the Mandarin feels embolden to attack him. So Tony's desire to help rebuild security and intelligence agencies, because privatized world security doesn't work, while at the same time trying to corral and control enhanced people makes more sense. No weird backslide from Ironman III in Ultron if Ironman III comes afterward.
Guardians of the Galaxy
Nu Spiderman with the kid. (So Tony isn't his benefactor and getting all up in his stand alone movie.)
Now comes Avengers: Civil War. The world is tired of superheroes running amok and creating chaos as they did in Ultron, Dark World, and even IM3. They want something to replace SHIELD so they feel secure again. Enter General Asshat and Tony who create the Accords, something Steve doesn't agree with. It's still possible for Zemo to frame Bucky to get the ball rolling, but it's more to reveal his past to the world, which was something the Avengers had been keeping secret, to ruin Captain America's credibility, tear him and Tony apart as allies, etc. And unless they intend on making something of the fact that Howard had super soldier serum later, I'd skip the plot line that it was Bucky that killed him. Mostly because it's getting a bit ridiculous how everything revolves around Tony in some way.
Guardians of the Galaxy II
Doctor Strange II (Which they reveal that Tilda Swinton wasn't THE Ancient, but AN Ancient and the Ancient of the comics was off screen doing something else in the first movie and they sometimes move about the world while another takes over their duties in particular locations but adopt the dress of whom they are stepping in for out of respect.)
Bucky Barnes II- Man on the Wall. (Yes, Bucky goes to space. After Civil War he just needs some time away and this would be a perfect way for him to eventually run into the Guardians of the Galaxy, which brings them back to Earth for Infinity War I & II.)
If anyone is interested... also, randomly, I've decided that Steve Roger's father was in the trenches when Wonder Woman marched across No Man's Land and he wrote about it, which ended up being the last letter to make it to Sarah Rogers, and Steve found the letter when he was a kid and read it so often that it's the reason he chose a shield as his weapon of choice when became Captain America.
So there you go. You're welcome?