My sewing room is in the basement. My DH finishedthe basement and we put the sewing room far away so people can not find it by accident. (hehe)
After a year or so, DH and my cousin put me in floating wood floors and it is great for swiffering up fabric scraps. The padding under laminate floors make it nice. Due to my age, he had to put ceiling fans up for the hot flashes so heat is not a big problem. Have a small heater just to make sure machines are warm.
Lighting is everywhere, large shop light over cutting table and ceiling fan over sewing machines (at serger end of table) and another work counter. Extra screw on positionable light over sewing machine ironing. Additional desk lamp above ironing board. Make sure several plugs and power cords. There will be positives and negatives to whichever room you pick. Go down and sit in it. Picture how you would set everything up that will save you lugging stuff back and forth until you know as your final answer. hehe Good Luck and have fun. T