It depends on how you use the room and which room the door leads into, I think. If you use this as the main sitting room/lounge I would be tempted to just put vertical panels to close it up, so you can store whatever under the stairs, and put the TV above the fireplace instead. If you do bifold doors I think you can get away with mounting the TV on one of the panels and the door can open in a way that won't bother the Tv. I have something similar in my new build, but the developers did not use the full length under the stairs so the storage 'room' is rather small. I use the remaining of the space outside to put an American fridge freezer (under stairs space is inside my kitchen diner.)

Makeup, jewellery, etcShoes in shallow section, drawers in deep section fitted to recess with entertainment on top.4 metre high ceiling in apartment with strage issues...pull down hanging racks Teenage boys would rather room space than clothes space but this is a little of everything for a late teen for clothes, sport, study and sleep. His overflow clothes are stored in the desk drawers, which double s file drawers.

http://www.houzz.co.uk/pro/katibushell/kbid-ltd  Lovely team at KBID with design and make in their own factory

A photo would be great, thanks. My imagination is failing me! The chest of drawers is fine but I really just put it there instead of getting rid of it when we changed our main bedroom furniture. Was surprised to find it fitted perfectly! I don't think we could attach it to the wall where it is because it's just a paper thin partition to a wardrobe in the other room. It's pretty big for the room if we move it out the alcove.