I have a 43" X 25" permanent center table mounted between two 2" (French knotted) stainless poles that anchor to the bilge to the cabin top. It's centered (just a tad forward) between the main bulkhead and the forward side of the icebox. It folds in half lengthwise pretty much on the center line of the boat making it easy to move forward/aft around it. There is more room when the leaf is dropped but there is still enough remaining to be useful when sitting on the port settee.
Like Jay, having seen the fold up tables at first I thought I might have preferred that style because when folded up the entire cabin is open. However, having lived with mine for a while I now like it. For one, the two poles are solidly anchored and come in really handy when moving forward/aft when underway. Secondly, being a liveaboard I seem to find myself sitting at it all the time anyway, staring at my laptop, eating, having a cup of coffee while reading, etc. (just like right now :). It's rarely in any other configuration. I'll post a pic if anyone is interested.