The whole point of the thread was to give people the chance to name one song, that, when they hear it just screams 19--'s. I don't think there is a right or wrong answer. Of course there shold be differing opinions, and that is what I wanted to hear from you guys, other fellow Zeppelin fans.
Thriller, Roundabout and Freebird are all good responses. Along with the one person who actually listed their four choices.
If I played 1979 vs Everlong vs Smells Like Teen Spirit, I think that most people would agree that Nirvana would be chosen as the definitive rock song of the 90's.
I also agree that Stairway to Heaven isn't the best Zep song of the decade. But if you mention Zeppelin to just about anyone, they immediately think of that song.