(I'm not making this a regular thing, don't worry).
I used to say sitting room, but like settee, at some point I switched over to living room. I'm a Londoner, but had a Midlands mum.
Following on from the other post, I think if you say settee, you probably say sitting room. If you say sofa, you probably say living room or sitting room . Lounge definitely goes with couch.
Which term do you use, what region are you in/from? I'm not counting front room, because that's a separate thing imo. The front room is the good room, or "the parlour" if you're posh.
I'm originally from London and my parents would always say living room and sofa.
My boyfriend's mum refers to one room in her house as a sitting room, and another as a living room. I can never remember which is which, despite living in that house for a number of years.