Worlds featured in the stories of those soft-cover issues:

Apokolips
Avalon (DC Comics)

Bismoll
Bizarro World
Braal (DC Comics)

Citadel (comics)
Colu
Competalia
Czarnia (comics)

Daxam
Dryad (DC Comics)
Durla

Gemworld

H’lven

Imsk

Korugar
Krypton (comics)

Mogo
Multiverse (DC Comics)

New Genesis

Oa
Orando

Puppet Planetoid

Qward

Rann
Rao (comics)
Rimbor

Shanghalla
Sorcerers’ World

Takron-Galtos
Tamaran
Thanagar
Tharn
Transilvane
Trom
Tyrraz

Warworld
Weber’s World
Winath

Xanthu
Xolnar

Zuun (DC Comics)

 

Details here.