The game features new NPCs, such as Servo, the Tragic Clown, and the Grim Reaper. Santa Claus will come if the Sim leaves some cookies beside a Christmas tree, and a fireplace. Santa will leave presents under the tree. The Tragic Clown visits depressed Sims who own the Tragic Clown painting in order to cheer them up, always failing miserably. Sims can contract an illness from a bite by the guinea pig included in this expansion. The Grim Reaper performs the final rites for deceased Sims. Living Sims can plead with the Reaper to save that particular Sim, which will result in three possible outcomes: death, resurrection, or a zombie.

Livin' Large comes with many new objects, such as a crystal ball, electric guitar, chemistry set, and magic lamp. Some of the objects had new NPCs associated with them. For example, a genie appears from the magic lamp and a booth comes with a Servo.

Multiple neighborhoods were introduced in this expansion pack, allowing the player to have up to five new ones.