Your main bedroom.
The room features a sorting chest for the Fate cards and some jewelry chests to store whatever you like and large dressers. The back dresser has a hidden panel that leads to a secret vault. The vault can store septims and will dynamically display your wealth up to a value of 2 million.
The master bedroom also has a "Dovahcloset" that can be used to sort gear and costumes and enable you to quickly change between preset outfits. This closet system consists of 16 drawers and two activators. One activator will sort your currently equipped outfit into the chosen drawer on a menu, the other activator will equip the contents of the chosen drawer from a menu list.
If you have Cloaks of Skyrim or the integrated Cloaks of Skyrim from Complete Crafting Overhaul Remade installed, you also have access to the Cloaks Dresser from here, where you can display unique cloaks.