I am not retired but all the kids are gone. Finally built the house we always dreamed of and I have a workroom on a detached garage where we keep our dogs. My wife likes to go to bed early so I have all evening in the workshop/doghouse. It has a window unit, fridge, TV and DSL internet so it is not a hardship
It is important to have "space" and an area your own. We learned a long time ago that it irritates the hell out of her to see me sitting on my ***** watching a worthless program on TV and that it irritates the hell out of me for her to walk by with a disapproving look.
So make your own space, let the kids join you ocassionally, and spend some time there. You will find that you will spend more and more time there and she will object less and less. The amount of time will vary according to your family schedule. Even before the kids were all gone I found that spending some time apart keeps everyone in a better humor and the time you do spend together is better quality.