I have had basement sewing rooms in some of my homes and converted bedrooms in some of my homes. Each has its own benefits and drawbacks. When we moved to our retirement "farm" this house had a big attached garage that we didn't need because it has a 4-car garage building very close. I love my garage studio. What I have found makes the biggest difference is lighting, electrical outlets, storage and lack of isolation (not in that order). I have a stereo/radio, TV and Roku to draw me in and keep me in my sewing room. I have never even thought of having 2 sewing rooms because I love having ALL my tools near me. You have to think carefully about the real reasons why you don't get down to your basement room. They may have a simple cure.