Just a nice big mall, kind of like how the abandoned apartments were like, but a mall with maybe some zombies in it and a security camera system in a security office, if possible. Maybe even make certain lootable areas accessible with different cards, like the security office and maybe some other typical "staff only" or restricted access areas. It would be a fun place to loot and run around killing zombies to fulfill our zombie-apocalypse-in-a-mall-fantasy needs.