As much as I'd like to make this a post about well-designed, posh offices à la Architectural Digest or Domino, when I say "essentials", I actually mean "essentials": those things I need to do my work (and do it well).
Function - As much as everyone likes teeny-tiny fashionable desks where everything is hidden away in invisible storage bins, that vision is simply impractical in my world. I have a jumbo corner desk that is reversed in the room, so that I can see the door front of me and the windows are at my back. This allows me to work in (mostly) natural light, see coworkers coming and going and, generally, work efficiently. While my desk is neat, I work best with visual reminders, so there are stacks of papers lined across the front of it and sometimes on the floor behind (sigh), as I keep track of various projects. Add to that: piles of business cards, file folders, bulky computer monitors and a 1980s-era dinosaur phone and you pretty much get the picture.
Creativity - As much as I appreciate function over frivolity, I also want someone to have an idea of who I am when they enter my space. (All work, no play, etc.) There has to be a little whimsy: postcards from past travels to remind me why I'm at work in the first place, a sports pennant of my favorite football team, plants in the windowsill, a daily photo calendar and local flyers from events around town, all add color and personality.
Essential Supplies - Comfortable sitting chair for guests who need to come in and vent, floor lamp to avoid the dreaded overhead fluorescents, corner bookshelf,
Snuggie long cardigan, white legal pads, black gel pens, colored Post-It notes, my favorite stapler, small ceramic space heater, chocolate and tea, lots of tea. (Is it obvious yet that I work in an icebox?)
Currently Coveting - A nice rug to cover the industrial greige carpet that is ubiquitous in the building. More than anything else, I think a rug would bring a level of coziness that is noticeably lacking in our office.