Allow everyone to vote in BOTH primaries
In most states non-party voters could vote in any primary.
You know what happened in states where Democrats could vote for the Republican primary candidate? Many of them came in and voted for Trump. Because they thought, who could possibly lose against Trump?
Then they went back to the Democrat primary and voted for the one person that could...
Ranked preference / instant-runoff voting in primaries and in the November general election
Why would the results have been any different? If you add up all the Stein/Johnson votes it's not enough to have the whole election results turn out differently, even IF all such voters listed Hillary second - many would not have.
Eliminate Electoral College
And have all candidates spend the whole time in Texas and California, ignoring the rest of the country? No thanks.
You have no idea what a wildfire you are trying to ignite, to have the entire rest of the nation feel utterly ignored.
Possibly also eliminate President/VP "ticket" and let #2 vote-getter become VP
You remember the VP from the movie Dave? Yeah.