I thought to check out some of the top grossing movies:
1999: Phantom Menace
1998: Armageddon (behind Saving Private Ryan)
1997: Titanic
1996: Independence Day
1995: Batman Forever (behind Toy Story)
1994: Forrest Gump
1993: Jurassic Park
1991: Terminator 2: Judgement Day
I have to vote for Jurassic Park as the movie that most defines the theme of the 90s. "Plot doesn't matter, as long as we have cool, computer-generated effects." Other top-grossing films include Men in Black, Twister, Mission: Impossible...heck, The Flintstones made over $130 million...