Closets are often overlooked in buildings. However plenty of details can be added to closets in your maps.
You can add them under stairs, by entrances, in bedrooms, etc.
Shoes/Shoe-racks.
use:
/summon Item ~ ~ ~ {Item:{id:leather_boots,Count:1},Age:-32767,PickupDelay:32767
to place leather boots on the ground in item form. It can never be picked up or despawn.
You place these on iron trapdoors to look like shelving units.

You can also add chests and enderchests as well as MHF_Chest skull and c418 skull {jukebox}
/give yourname skull 1 3 {SkullOwner:MHF_Chest}
/give yourname skull 1 3 {SkullOwner:c418}.

You can also add a bookshelf or crafting table with a potted plant for a nicer look.