Suggestions:
Lal - Erick Avari
Santiago - Angelina Jolie
Morgan - Morgan Freeman (I wonder if he can do a backflip...)
Zakhaorv- Possibly the guy who plays Kahn in the second Star Trek movie
Deirdre - Anyone who looks good naked
It would be hard to make alpha centauri into a movie, considering that there are seven charactors to focus on, as well as many, many...; many battles.
If it were to be a trilogy, i think the first episode should invovle the conflicts on earth (political, finantial, finding the leaders, etc) then the journey, then the conflict that leads to the faction split and ending with the pods heading toward Planet.
The second episode, I agree, would be boring; but it could be spiced up with intence fights with mind worms, a possible faction accidentally landing in the ocean, a few riots, and mabie a leaky pipe or two in a pressure dome. This one should end around the time a planetary governor is elected.
The third and final one should start with some kind of war sparked by an atrocity (genetic plauge, mabie) leading to an immediate destruction of a faction. At this point i think the spartains should have held a final, dramatic Alamo-type battle just for the purpose of getting rid of a worthless faction (in a way, this could fit in with the Assasins base sending the "Mary had a little lamb" message). After that, who knows what would happen. Planet would kinda need Deirdre for the ascent to trancendence, Sister Miriam and Zakharv would still be at each other's throats, Lal and Morgan would be fussing about each other for god knows what reason and Yang would just be there, doing his thing.
I think it would be kinda neat if one faction barly escapes destruction and builds secret bases under water. Lots of 'em. All of the under water bases should then build drop pod units, tanks, planet busters, cruise missiles and planes. Then all at once they surface and launch a massive attack, eliminating a faction or two, and bringing another one to its knees.
Mabie the solution would be in a ten-episode movie series, where some of the focus is more on citizens (like an epic naval battle for instance)....or would that require 25 episodes?
Mabie the final answer is Alpha Centauri should exist just for the game, and shouldnt be made less awesome by making them into movies. Who knows, the possibilities are endless.