I had a private office for eight years, its not really meaningfully different from a cubicle (I've never worked in an open floor plan). I mean, I could close the door rather than putting on my headphones if noise was bothering me, I could have phone conferences in my office, and I could have private phonecalls without stepping outside. I also had more room for all my crap (ended up with a few old computers sitting around). But those improvements are very, very minor.