Forget the new blockbusters...since the technology wasn't there yet, what about all the truly hideous blockbusters of the past 20 years? I'm glad that they grabbed Titanic (that would've been my first choice) and Independence Day, but I say this was really the prime period for big-budget movies that thought they were masterpieces but were actually big piles of cliched dialogue, poor acting and...well...poopie. There's so much more to riff. Please oh please, where are:
Twister (anything that stars Bill Paxton is pure RiffTrax gold)
Face/Off
I Know What You Did Last Summer
The Passion of the Christ
Navy SEALS
Ballistic: Ecks vs. Sever
That said, bless you guys for the riffs of all three Star Wars prequels. You've made the world a better place to be.