Where does Fallout 4 store save files?
On the PC version of the game, save games are stored in My Documents > My Games > Fallout4 > Saves. ("%userprofile%\Documents\My Games\Fallout4\Saves")
My PC has the save location at:
$OSDRIVE:\Users\$USER\Documents\My Games\Fallout4\Saves
Where $OSDRIVE is the drive letter of my operating system (windows 7), and $USER is the name of the logged in user.
example: C:\Users\user1234\Documents\My Games\Fallout4\Saves