OK it's not much but it is something to think about. At a Television Critics Association event to promote the upcoming TV series Revolution, Jon Favreau talked about what he was planning when he was originally attached to direct John Carter of Mars at Paramount which is reported at http://www.craveonline.com/film/articles/192797-john-favreau-reveals-his-original-plans-for-john-carter and revealed that his plans for it were much "smaller" than Andrew Stanton's finished film:
“I probably wouldn’t have been as ambitious. I think both of us really appreciated the source material. Stanton started to weave in elements from the later books. I probably would’ve told a smaller story. As we were developing the script it was much more the experience of John Carter being found in this new world and him coming up in A Man Called Horse kind of way among the Tharks and then opening up the world slowly.”
I'm sure some will think Stanton's approach was more appropriate but if anything the "smaller" approach might have worked better. Oh well some food for thought.