So, I'm just going to start playing and I'm trying to import my save file. The latest save file from Witcher 2 is right about to talk to Letho. The game doesn't appear to be making a autosave file right after the credits and what not, is it supposed to?

Either way, how would the game know I let Letho (I don't know if he's in the 3rd game or not, but feel free to spoil me on that) go or not in that case? I think I might be missing the save file I want or am failing to generate it.

Nevermind, I got it. Appears that the save file didn't show up in my directory until I relaunched Witcher 2 again... kind of odd, so when I copied it over, the file was missing. I see a new autosave and when I loaded that, it was just before Dandelion and the credits.

The save file is there, it's an auto-save, but the stupid game displays it out of sequence -- you need to carefully check the time and date of the save, and select the save by that criteria, provided you did not play after the end game.

Go into Witcher 2 and go to the Load menu.
Look the progressive number of the very latest save (it should be an autosave).

Go into Witcher 3 and look for that save number when importing.

Or you could just use "Simulated Witcher 2" choices. This is easier and more configurable than playing Witcher 2 if you don't have time.