If you spend most of your day in your working area the least you expect is to be inspired by it and feel comfortable and pleasing while there. I'd definitely insist on a great lighting source (a must for non-headache working hours) and a large window to get you connected to the outdoors, nature even better (and provide you with ample daylight as it lasts). Secondly, an abundant place to work on, aka a large desktop, would get extra points. And storage. Shelves, drawers, cabinets, boxes, folders, anything. Taking storage into careful consideration is mandatory and, somehow, a non-ending duty.
I still have some issues on my lighting in my home office. Although I get enough sunlight during the day, as soon as the sun sets I feel like a miner working under earth. I'm thinking of adding a floor lamp next to my desk (I love floor lamps!) and that means I've got some shopping to do (or, even better, some DIY).
How is your working space? Do you get a chance to update/redecorate it and what would you like to change?