Like most old things in our house the floor in the closet was gross, so we put down a new cork floor since we're out of the hardwood we used in the rest of the house (finally). I was pretty amazed at how nice cork is these days. We may have to look at it more seriously when we do our basement.
With the walls built, floor in and trim done we built an L shaped set of shelves and installed two levels of hanging on one side of the closet. Here it is in action. We unpacked three more boxes today (yes, 2.5 years later we are almost unpacked). We also moved most of the stuff from our main bedroom closet since that space is next on our hitlist. So this is a bit more than the closet will normally need to hold but it does it pretty well.