We used to dream of putting an entertainment room in the house, but space has always been a problem since our house has a limited floor area. We have the essentials like 3 bedrooms, kitchen and dining area, bathroom, dirty kitchen, porch and a garage but we couldn't add up extra rooms such as a working area or a study room, home office or an entertainment room. Because of space problems, I became a number one fan of storage solutions.
My daughter used to tell me before that it would be nice to have an entertainment room which they can also use to accept visitors but I have turned down the idea long ago. She even wanted to have some musical instruments in place such as guitars, pearl drum set and keyboards. I told her though that such would be a waste of money and effort as I'm pretty sure that it wouldn't be used more often as we are all busy in the house. For now, she is contented with her very first guitar that we've bought a couple of years back. (lol)
Anyway, if I would add up additional room in the house, I prefer an outdoor space or a home office. That's my priority for now. (winks)