basically the 'ending' would be something along these lines.
bleh, ok, gonna do more of the movie cause too much info comes into play that it would be the whole movie.
The clone wars are wrapping up, this uses that the clone wars cartoon handles all clone war info. so basically we would come in with no grevious because he has been killed after killing many jedi (leaving plenty alive for vader to later kill). Anakin still seems like a good guy, he may be working with palpatine but we dont know and dont see any of this, we may still see Palpatine manuevering him as a senator but no linkage of anakin to palpatine as far as a jedi/sith connection. So the war is ending and the Jedi think they are close to victory, the Supreme Chancellor (Palpatine) seemingly has pretty much regained control of the senate again, and the Jedi have are going after what they think is the remainder of the resistance, but have started to do some rebuilding.
Due to his performance in the Clone Wars, Anakin is no longer a padawan and Obi-Wan reluctantly takes on a new student at the behest of the Jedi Council (as do most masters/knights) to help rebuild the Jedi. (possible could give Anakin a student as well) this could allow for some good story and stuff to help build tension between Obi-Wan and Anakin. Obi-Wan is still trying to teach Anakin who doesnt want to learn, he thinks he knows it all, the Jedi Council has made him a Jedi Knight after all. Exact details and all im at a lack for right now, but basically at one point it gets pretty serious, they are on a joint mission to destroy one of the last remaining resistance sells, or independant and they meet up, i think joint works better. Obi wan is leading it, but Anakin doesnt like that, he doesnt want to take orders from Obi-Wan anymore, he is after all a Jedi Knight, and a more powerful one at Obi-Wan at that (at least in his eyes). They end up fighting and during hte fight anakin gets knocked into the pit, Obi-Wan tries to help him and while he is pulling him up Anakin pulls Obi-Wan down and he is now on the edge...Indiana Jones and the Temple of Doom struggle like the one he had with the witchdoctor guy on the rope bridge and anakin falls into the lava...Obi-Wan is mortified...he returns, his mission unfufilled, to give the bad news and all that. (Padme is already pregnent at this part).
Somehow the jedi get intellegence and he finds out somehow that Anakin survived and is being held on a starship by the 'seperatists' and Obi-Wan (possibly against the will of the councel) goes to rescue Anakin. Meanwhile the clone army is preparing its final attack against this ship. Kenobi gets aboard this main ship of the seperatists and is searching for anakin, this is where he comes to the Med center and sees the burnt cloths (solemn music) and lightsaber (he now has Anakins saber to give to luke in ANH). As he 'gets teary eyed' over what remains of Anakin, he hears a vader-like voice...a raspy JEJ, partially through the voice modulator but no helmet. the voice says 'Your friend is no more' (maybe dead, seems a little strong though) He turns and we see vader, helmet off, face obscured by Obi-Wan. The camera pans around as the helmet is lowered and when we finally see the face it is covered by the helmet, he is in a similar device to the meditation chamber in Empire, just not as elaborate. he stands up and bam, we see vader. Obviously they fight, it wouldnt make sense otherwise or would make vader look like he has a soft spot for Obi-Wan, hinting at his identity and that he's not all bad. so they fight and (remember the battle going on outside at this point from the clone army) a torpedo hits the ship near them and causes sparks and dusk and equipment to fall. Obi-Wan, knowing that vader is more than he can handle (again, this hints its not Anakin, because they are evenly matched during the lava fight, and obi-wan maybe even seems to have the upper hand at points) takes this distraction as a way to escape.
Now Its possible at this time that Palpatine makes his move to take control and the Jedi Temple gets wiped out, we see people like mace die but dont see anything of yoda, Kenobi comes back to a ruined temple and we then see him go to padme (silent, only music playing) he tells her something (we cant here it cause its silent) she starts to sob...she has to die at this point, maybe another attack on the Imperial City and as they try to make there escape she gets killed and this is when the Luke pass off occurs) Actually, as much as i like that silent scene with sad music with the silent message we assume is Obi-wan telling Padme Anakin is dead, i think that has to go. OK, i think the best way to handle this is he comes back, Padme is at the Jedi Academy Nursery with luke and leia, there are other children so we dont know its leia, she isnt actually shown or somehting, this scene may need ironing out but hte concept is here. where there are children playing..he's talking ot yoda out side of the room and while we cant hear it we know they are talking about anakin being dead and telling Padme (though its really that anakin is vader
). As they go in to tell her there is an attack on the temple...Chaos ensues, Jedi are dropping like flys...Yoda, Mace and Obi-Wan take action. Obi-wan however goes to help padme while the others go into the thick of it (we can see Mace die, but Yoda's fate is left uncertain. Bail Organ meets up with the fleeing Obi-wan, Padme, and Babies (has to be done to show only one). they get to the hanger and just outside padme is seriously injured and she gives Luke to Ben, Bail Organa Takes off in his ship (he has leia) and Obi wan takes off in his. Fade to him landing outside the lars farmstead. Silent scene from the distance, Obi-wan telling them the news and giving them luke. We see the shock on Owen's face, and Beru takes the baby crying...Obi-wan heads back to his ship...scene cuts again to a balcony of the capitol building with Emperor Palpatine looking over troops of Stormtroopers. vader steps up into site...Evil type music is playing switching to Imperia March as vader comes in...usual star wars type transition to credits.-Darth Simon
*edit: Imagine what i would come up with if i wasnt at work