In our old house, my sewing room was in the basement. It had no windows, and the ceilings were pretty low (8 ft) but was painted white and had 4 flourescent lights with 2 bulbs in each so it was very bright and not at all damp. In the summer we would run a dehumidifier in addition to the A/C. It was away from my family, but it's all I could do. When I was garment sewing, I would sew some things down there, then bring it upstairs to do some pinning. I also knit, so I did that upstairs when I needed to be with the family.
We moved last year and my sewing area is in our new basement. It's not finished, there are very few outlets, so I run stuff on power strips (probably not the best) and, due the 9 foot ceilings and the single bare bulb, it's dark. I can work OK on the sewing machine, but cannot make color matching decisions. We are brand new empty nesters, so I am thinking about having a secondary space in my son's old room with just a sewing machine and ironing board. Then I'd be upstairs. I'm not a fan of having half my stuff downstairs and half up, but whatever. It will be awhile before the basement is finished. Gotta keep sewing!!!