Office/Den Decorating Plan

Our current apartment set-up, utilizing the 2 bedrooms, has allowed for the second bedroom to be used as a den - with two televisions set up (for optimal football viewing: RedZone on one television, and of course, the Patriots on the other) and a couple of couches. It is essentially a second living room and it is definitely great to have the additional living space. However, the downside to this arrangement is that for 7 months out of the year (February through August), the room doesn't get used nearly as often. Yes, sometimes we use it to watch television when the one of us wants to watch something the other doesn't (Hello, Grey's Anatomy!), and occasionally I use it for projects, but for the most part, the room collects dust and the walk-in closet acts as storage that gets continually cluttered. In our new apartment, I'm hoping to combat this by creating a room that allows for multiple purposes.

As you look at this moodboard that I created for the new room, I need you to use a bit of your imagination. Okay, maybe more than just a bit ... but work with me here. See that desk in the middle? The beautiful sawhorse leg desk with glass top in all of its glory? IKEA only makes it in one color - black, and I want it in white. And if I'm going to take the time on an IKEA hack anyway, I might as well have fun with it - so I'm thinking about doing something fun with the legs - maybe a gold plated dipped look? I will keep you in the loop!
             
Aside from the desk, I plan on moving the Expedit bookcase that currently works as my nightstand into the room for the tv stand, finding a comfy chair to use, and finding some sort of shelving that works well with the room. I may end up using regular shelves, but I do really like the idea of floating ones. 

As for the colors? I will be painting! Yay! I know this is a rental unit, and I know we won't be there forever, but I just think that making a space feel like home at such a small cost is really something that I have to do. So I am. :) And, with the grey interiors, I will be adding some blue and white curtains and throwing in pops of yellow - focusing on colors that inspire creativity! 
What do you do to make your rental feel like home? Have you painted even though you have to paint back when your lease is up? What other ideas do you have to create an office/den area for multi-use?