When is the last place you can save in Fallout New Vegas to get all endings?

I'm playing through Fallout New Vegas and I'm aware that there are 4 mutually exclusive endings. I would like to see them all and get all the achievements, but I don't want to play the entire game four times.

Where is the latest point in the game that I can create a checkpoint save that I can go back to in order to get all endings?

After you've got the Platinum Chip from Benny, then talked to the Yes Man, save before you leave the Tops Casino. Once you leave the Casino your reputation with the Legion and/or the NCR will be set to neutral if you've gained any infamy.

Also, if you really want to save yourself some time you could go to The Boomers and complete most of their quests (just don't go speak to Pearl to finish off the Volaire! quest).

You will have to play through it at least twice though, because the of the Hardcore achievement. (It might also be a good idea to play through with a character with maximum Luck to get The Courier Who Broke The Bank.)