Vault 88 Enhanced
If you've got the Vault-Tec DLC installed you'll want to take a look at this mod that enhances the add-ons Vault 88.
The mod's full name is Vault 88 Enhanced: More Space - New Rooms - New Workshop Items - No Limits and it delivers on these promises.
With it installed, you'll get three times more building space, more than 50 vault dwellers, new room types, new decorations, new experiments, and more.
The developer will be releasing new content throughout the summer and fall so we expect this mod to improve as time goes on.
If you're unsatisfied with the vanilla version of Vault 88, give this mod a shot.