First, get the drywall primed. Then, consider a very light warm color on the walls (not necessarily gray for a basement). You have enough space for a seating area by the gas fireplace, as well as perhaps a games table or workout area, depending upon your lifestyle, in the section near the stairs. Then, decorate as you would anywhere else in the home- some artwork, area rug (even over the carpet) or personalized pieces.

Thanks, by the way the fireplace will have a 5ft wide by 7ft hi antique dark oak surround. We have to use it, and want to use it, it's 200 yrs old and beautifully hand crafted, from G G Grandma's house