I grew up in the 80's with WAY older brothers. I listened to what they listened to because THEY were so cool!.
So, Here's what I suggest:\( These are only a few of the old 70's AOR(Album Oriented Radio) popular bands.
Jethro Tull
King Crimson
Yes, ( NOT the 80's "group" with the album 918209 I think)
Genesis(early, When Peter Gabriel was vocals)
Moody Blues ( not my favorites)
Aerosmith
Boston( repetative sounding, all of the music focuses on lead vocal, all sounds vocals are the same..In My opinion not the best group either because of the style and voice same in every song)
ELO.. Ahead of their time with "Electronica" sound
Peter Frampton ( 1 album hit wonder)
Queen ( older stuff, actually, they have a pretty broad musical style, You didn't always know who the song was by.. i.e. I'm in Love With My Car( Jaguar Commercial..Thats Queen)Surprise!)
David Bowie/Ziggy Stardust ( Pre curser to "Punk")
Styx( same category as Boston, no matter what the song, you know who sings it.. no surprises)
Chicago.. excellent for their Jazz/brass roots
Doobie Brothers
BTO ( still popular today, in commercials)
Led Zepplin
The Who
The Doors
GTR ( I know this is actually later 80's, but with Steve Howell, Trevor Howard, Chris Squire and Max Bacon.. A lot of oldies in there)
Thin Lizzie
Wet Willie
Santana( STill timeless)
Eagles
Fleetwood Mac
Sheewwww, I can't think of any more right now.. But there are still a LOT of good ones