For the last ten years it's been a latte brown/grey, okay greige, 3 seater. I'm loathed to get rid of it as it still is so comfy, though somewhat worn and faded. Desperately trying to the find a drill, cotton or linen in a bright teal/ kingfisher/ peacock blue to re-cover. Something like this...

Because there is a lot of timber and dark paint in the room ( which i like) and because it creates a neutral background you could easily takes some risks. The problem with fitted plain and very light fabrics is the risk of stains showing etc. so I would choose a mix and match red ( not a blue red) in leather if you have the money or a blue could be good to match the painted area. Another idea is to have fabric covers in natural fibres like washed linen that can be removed and washed easily. Look at beach house styles for inspiration. Add colour in a new rug!

I think any colour rug would suit your lounge, you can be bold with colours or you can be soft with colours depending on your personality. As for a coffee table I wouldn't go bulky something streamline perhaps in a metal even a light colour timber. Have a bit of fun with mixing and matching.

Given the colours in your room, I think navy would provide great contrast :) Maybe a coffee table in the centre with some blue/teal/navy accents such as a dish, candle holder or vase might help to blend your new chairs and sofa into the room - along with some patterned scatter cushions. Can you add some lighting to the darker part of your room?