Okay here goes:
My headcannon of Presidents
Udall 1977 - 1981
Robert F Kennedy 1981 - 1989: Beats Reagan in 1980, has a successful 1st term, wins in 84 against Donald Rumsfeld who advocates a stronger military against Soviet Union. No Greed is Good, Star Wars Missile Defence, no tax cuts in this 1980s, probably no Yuppies (who knows)
Shirley Temple 1989 - 1996: after 12 years out of power, the Republicans finally take back the White House with former actress and California senator Shirley Temple winning the GOP Primary and the election, becoming the first female President in Blue Skies. Her running mate/ Vice President is none over than Hillary Bush, picked not just because of the connections to the Bush family but also as a way to modernize the Republican Party. Shirley is a unique President, fiscally conservative but also liberal when it comes to things like AIDS, abortions, the environment, much to the annoyance of evangelical Conservatives, but they more or less choose not to pick a fight with Shirley. She wins a second term against the democrats in 1992 (not sure who, Jerry Brown? Dick Gephardt? Joe Biden?) the most significant act of Shirley's second term is her decision to nominate former President and her one-time rival Bobby Kennedy to the Supreme Court which pisses off the hard right of the Republican Party. Bobby Kennedy narrowly gets confirmed but Shirley spends the rest of her term fighting her own party over legislative issues.
Hillary Bush 1997 - 2000: despite the infighting with the more conservative members of the GOP, Shirley is still broadly popular and uses her popularity to ensure her loyal VP Hillary gets the nomination. Hillary beats conservative commentator Buchanan in the Republican primary and is able to win in the election as a "third term for Shirley" becoming the second woman elected President. Her term is pretty uneventful, the economic is pretty good and Hillary tends to focus a lot on foreign policy. She is challenged in the primaries by Gingrich and narrowly beats him to the nomination. But during the election she is faced by none other then John F Kennedy Jr, who becomes the third member of the Kennedy family to win the Presidency.
John F Kennedy Jr 2001 - ? Kennedy's term does not start off great thanks to a recession caused by the Dot Com crash as well as GOP control of the senate makes his legislative efforts hard. Plus the threat of terrorism. However his wife Diana Spencer Kennedy is very popular with the American people, compared to "Guinevere" and nicknamed "the People's First Lady".