Time is running short and it looks like I'm going to have to just pick what I like best aesthetically and create a map that works best for a semi-sandbox style game to flesh out the Barsoom-inspired Mars campaign section of the book.
Here are just a few examples of Mars maps floating about the interwebs.
One of the better maps came in the John Carter Warlord of Mars boardgame/wargame by SPI:
Another one I like is from the almost-RPG John Carter Adventure Handbook published by Heritage models:
But, of all the various maps of Mars out there, by far one of the worst is the one in the ill-fated Warlord of Mars published by TSR - which was quickly rescinded for copyright violation:
This is a very interesting topic, worthy of several posts, so I'm sure I'll have more to say about it in the coming days as I finish up the version of this map for WotRP.
Discuss this on the WotRP forum, where I'll be posting more details and images.