Bob, I'm probably just a bit older than the "younger generation" you talk about (i'm 27 and just a bit too young to be Gen X) and unfortunatley I didn't discover Zeppelin until about 19. But I do know that Zeppelin is the band that helped me realize that music could be great and reference literature at the same time. That it could have weirdly- kind-of-too-long tracks, like Carouselambra, and still have "Babe I'm Gonna Leave You" and "When the Levee Breaks" and the others you mention.
My friend AW had a monster home theater set up in his apartment senior year, and when the Led Zeppeloin DVD set came out, I think we all had a religious awakening watching "In My Time of Dying". on. Once, after we had all be drinking, he refused, which led to:
GR: If you don't put on In My Time of Dying, I'm not going to order us Pizza.
AW: You're going to lose this one.