I call it VIP lounge due to the size, only seats about 3 comfortably.

This is a 3 seasons room w/a ~20ft vaulted ceiling, (previously uh-heated), added the patio furniture, computer speaker system w/sub woofer. natural gas, vent-less fireplace. couple lamps...and VIOLA my winter time VIP Lounge. I added weather stripping to the door going to the rest of my house cuz the wife hates the smell, worked like a charm. Usually its just me, and my twin brother stops by about once a week, ill have 1 or 2 more close friends in there on occasion. Got a 15x25 shed electrically heated for when the "boys" come over.

For venting there is a window about 12ft up on the wall i stuck a double fan window fan in it, (the one with the pull out shroud that closes the gap between the side of the window frame and the fan) and plugged it into in outlet powered by a switch. ill post a picture of that too.