I'm reading Heinlein's book The Number of The Beast right now. While it's not my favorite of his books, it's one I like, and every time I've read it, I've intended to make a list of the worlds the characters visit.
Really, the book forms a who's who of classic science fiction novels. A lot of them I don't recognize at all. If you recognize one of these worlds that's not identified, or otherwise have more information to add to the list, please leave a comment to identify it.
The books include:
Worlds the characters visited:
The Edgar Rice Burroughs Mars series
Baum's Oz books
Who the heck wrote that world with the orthinopters (part two of The Number Of The Beast)? Is it a Heinlein creation?
The inside out universe?
Alice In Wonderland by Lewis Carrol
The Lensmen (No book or series title) by E.E. Smith
Heinlein's Future History Series
The Dorsai series by Gordon Dickson
The Darkover books by Marion Zimmer Bradley
Heinlein's Stranger In A Strange Land
Isaac Azimov's Nightfall
Galactic Patrol by ?
Larry Niven? (No first name given)
Poul Anderson? (No first name given)
The World of the Hobbits (J.R.R. Tolkien's The Hobbit and/or The Lord of the Rings)
The Sword In The Stone
The Once And Future King (TH White?)
Other Robert Heinlein related posts:
Time Enough For Love