Hi Fiona your list of furniture looks right to me, one option
would be side tables instead of a coffee table if the space available between
your fire and new sofa becomes too snug.
Placing lamps on side tables adds to the mood setting of the room and can
create a lovely warm, snug feel. Another
idea is a flower arrangement, or two, to add colour and life into the
room. A mirror is great to increase
light in a room; you could locate it above the three-seater sofa rather than
the fireplace. I always like to add some
storage into a room, especially with young children a foot stool which doubles
as a handy storage box could prove useful!
Finally, but by no means least, I’d suggest a piece of art hung either
side of your fireplace and more photo frames on top of your fireplace. Hope that gives you some ideas! PB

Sounds good. How many people do you need to seat as I think a 2 & 3 seater & lose the armchair. Nice large mirror above the fireplace. Rug & coffee table or side tables with lamps. Storage ? Maybe some shelving in the fireplace alcoves. Is there a separate dining room or do you need a dining table at one end ?

Thank you so much. I have the rest of the house to tackle too!! But one room at a time. It gets a little overwhelming when you start to look up professional photos and ideas. But I really like your suggestions. I'll post a photo once I'm finished :) Thank you!

I have to agree with nudejude regarding the upholstered furniture sizes and positions. The room looks long and narrow, so placing 2 chairs or a 2 seater sofa opposite another 2 seater would allow you to enter through the door and walk, unrestricted, through to the opposite end of the room.

An area rug between the sofas, large enough to fit under their front legs and perhaps a clear coffee table in glass or Perspex between would make a great conversation area.

There may be enough length to the room to use a console table behind the sofa nearest the double doors with 2 small occasional chairs. A pair of lamps would provide light for the sofa and for the chairs. If the chairs are needed, they can be brought into the main conversation grouping.

A Roman blind, with or without the curtains, would set off the window. Throw cushions in a variety of patterns and colour, will add interest to the upholstered pieces.

Good luck and enjoy your home.

Thank you so much. I had to read the ideas here a few times to really imagine what your suggestions would look like (I'm very bad at visualising!!)

If I create a conversation area around the fireplace, that would leave me with a big empty space behind the sofa - between the sofa and the window?

You can leave a good space between the sofas / sofa & chairs, they don't need to be on top of each other. You don't appear to have given room dimensions, so it's hard to tell how much space you will have, but I would suggest start off with the sofas / chairs and see how they look once you have them in place, and then consider adding other furniture to the room if you still have space and feel the need. I believe the optimum space between the sofas would be between 5 and 10 feet, then allow a good 18 inches between the sofa and a coffee table to save bumping your knees. Take a look at this pic it might help you with the visualisation:

http://alicelanehome.com/facing-sofas/

When using a coffee table between opposing sofas or chairs, make sure that both sides can reach the table comfortably. Without a coffee table, you can space the sofas further apart, but no so that you need a loud hailer to make conversation. You can always increase the width of the coffee table (square instead of rectangular)Also, try to keep the front edge of the sofas in line with the hearth corners or slightly further back, but no further in.