If you've got your mind made up re:desk, then you should have it. My space is only about 3' deep, and w/a chair, I would have been sitting in the doorway~~I took the door off and have a curtain panel on each side. There's a ceiling light, but I also hung wall lamps on each side wall for more direct lighting when using the computer. I have them about 8" from the top of the desk/shelf. I've also hung a large bulletin board on the back wall, with a few wall accessories/family photos. Oh, I didn't mentioned I painted the closet black, including the ceiling~~it makes for a very cozy space, as well as a topic of conversation. ;o)

I'm not a fan of TV's over fireplaces. I would close up the niches if you could and then use a console with the TV above it. Since you already have limited wall space with all the windows having the niches is just overkill.

I like what judrand05 said. I'll add one caveat to the Philips Hue lights, the bulbs only go up to 800 Lumens. For larger rooms, 1000+ Lumens is better if you use fewer bulbs. Also, a ceiling light would typically create more light. I'd still try them, they are easy to return if they don't work for you. When my Uncle re-did their whole kitchen area they installed rows of high-intensity white LED lights on the ceiling. As a result, their house is as bright as day during the night. My aunt claims it helps her read at night as her eyesight is not as good. Been jealous of that light setup ever since :). Most apartments/houses I've seen are underlit.

Maybe repost as a 'design dilemma' or on 'home decorating'? It looks like your space is about five feet wide and can extend down quite a bit. What do you mean by two computers, could you be more specific how many monitors, printers, etc. Do you need storage space for files for your work, or wall space to post instructions or directives, for example? How many people are in your household -- do you need visual privacy? Is your home computer mostly for web surfing? Good luck!