I keep a fairly small working surface for a reason...though most people know me as a de-clutterer, I can be a bit of a hoarder. My taboret measures 20x24 inches (it's actually an IKEA butcher block covered with a piece of glass) which has two shelves underneath it for extra supplies (paint, tube wringer, mark-making tools...and anything else I just can't seem to let go of for whatever reason) and the surface is currently a little crowded. Love having my radio nearby and the lamp is great for extra light as I do work in a basement.
The room itself is quite large (though I'd love an even larger space), measuring 10x15 feet and I tend to keep the floor space fairly empty so that I can move around while I work at my easel. I like to step back frequently to check on composition and colour. I also have a day bed in my studio so that I can be lazy and lie down while I look as well...it also makes a great surface to wrap art and sits at a nice height since I am rather vertically challenged at 5'2". Counter height is much too high for me to work comfortably.
Whenever I need more space (to stretch canvas or work on a larger piece) I move into my family room which measures 15x34 feet. And though it's all in our basement, we live in a bi-level so I do have plenty of large windows. I feel very fortunate to have so much space to play in.