One of Led Zeppelin's biggest hits is "Stairway to Heaven" which starts with a meandering guitar line in a minor scale and then gets heavier with some interesting lyrics.
https://www.youtube.com/watch?v=xbhCPt6PZIU
Another cool song is D'yer Maker which has a common interval pattern and has cool vocals and all around a catchy tune.
https://www.youtube.com/watch?v=xje-1sw3T0s
"Immigrant Song" is another hit of Led Zeppelin, all around rocking with great bass drumgs and electric guitar. The vocals are also pretty cool.
https://www.youtube.com/watch?v=RlNhD0oS5pk
Really great you can find concerts on youtube and really get to experience this music as it was played.
https://www.youtube.com/watch?v=NfwZfGAKyec
"Kashmir" is another cool song of theirs that has an intense guitar riff and intricate vocals.
https://www.youtube.com/watch?v=hW_WLxseq0o
"Black Dog" is another rocking song. Zeppelin is all around a very rocking band!! I will have to research if its about a dog or what someday maybe.
https://www.youtube.com/watch?v=6tlSx0jkuLM
"Whole Lotta Love" is another hit of theirs that like all their songs you can frequently catch on radio stations today. https://www.youtube.com/watch?v=HQmmM_qwG4k
Though the song that follows is probably my favorite. I also really like "Over The Hills and Far Away" it takes a while to get rocking but the foreplay makes it great.
https://www.youtube.com/watch?v=TvG4VGnjpsg
One of my favorite Zeppelin songs is "Tangerine" which is a love song it has cool instrumentals and interesting vocals.
https://www.youtube.com/watch?v=79JcPZNLCTY