The "Benevolent Leader" achievement (100% happiness in a large settlement) is far and away the hardest in the game to unlock. It takes hours, resources and a silly settlement to get due to bizarre behaviours and bugs in the happiness mechanic. What started as a genuine attempt to create a cool settlement and to get the achievement at the same time eventually became a grind and required turning Sanctuary into a ridiculous place just to make the settlers happy.

But it's done now and here is the save file. For anyone who wishes to save themselves over a dozen hours and contorting their settlement to ridiculousness, this save will pop the "Benevolent Leader" achievement within a few seconds of loading.

Notes:
- It is an autosave after waking up with happiness at 99 and rising, hitting 100 shortly after loading.
- This is a post-main game save file with all main and most side content completed already.
- I used the console for materials, perks and stats post-game to have some fun, try different things and work toward this achievement.
- This save uses the base vanilla game (no beta patch) as of 28th Nov. 2015.
- This save was made without any mods so should work on any version of the game with any combination of mods.

To use, please unpack the file into your FO4 save directory, which is located: \Documents\My Games\Fallout4\Saves
Then in game, it will be "Commonwealth - 4d 23h 38m" with the screenshot of a bed.

Please let me know if there are any issues, tho I have tested it multiple times with several configurations without one. Just load it up and wait a moment, "Benevolent Leader" should pop quickly. All the best.