Covenant...nice idea, but I too feel that it would most difficult (if not Impossible) to "tell" the story...a lot of it is internal and that is really hard to show.
But if it was done correctley in such a way where the audience would have an empathy toward TC and was made to fall in love with "the Land"- only to watch it darken over the 1st trilogy til the end, they might be able to feel the implied paradox inside of covenant that is textual and hard to communicate through the media type : Movies, Films, etc...its is not a happy story, TC has some serious grim events happen it is would be tough to put those things in a visual adaptation to a mass market and have it understood...but if someone pulled it off, it would be fantabulous. At One Time...many moons ago in my wild foolish squandered youth, I had once attempted it as something to do, but I had not the skills to handle the material. My attempt at a Ringworld script was much easier, but got basically bored manually transcribing text by hand to get a start.
Bunch of Niven would make good Sci Fi Movies-
Above mentioned Ringworld and followups
Dream Park and the others.
Mote in Gods Eye (first contact at its finest)
Legacy of Heorot (very scary monsters--lots and lots of them GRENDEL!!!)
Lucifers Hammer (I know there are other Comet crashes Earth movies- this is the big one though)
FootFall (interesting take on the venerable Alien Invades Earth plot device)
and for the really adventuress:
Inferno (sci-fi take on Dante)
Others:
The Long Run-Daniel Keys Moran (good really good)
Tailchashers Song- (think cat pov like watership down w/ da bunny rabbits and flavor with fantasy elements good very good)
Master of Five Magics and followups.
Incarnations of Immortallity- (Piers Anthony series good oh so good)
Four Lords of the Diamond- (Jack Chalker good good it is)
and the last two may shock or disturb you, but IMVHO very good reads:
Battlefield Earth (the story LRH wrote not the rotting refuse that was filmed)
and as a serial, which is how it is "organized"
Mission Earth Volumes 1-10...yes, LRH dectology opus...no one else could have written it. Its one of those things that people will either love it or hate it. It is not for the faint of heart nor those with delicate sensablities, but I found it to be quite enjoyable experience slogging through a 10 volume narrative. Others I had lent my copy either finished it or gave it up cause they didnt like it and felt it "grind" from event to event. The ones who finished enjoyed it tremendously. I feel if not censored and depicted as "satire" it would be a very wild ride.