That heat pump doesn't look too bad. It kind of blends in, and it's above eye level so it's not immediately noticeable. I like Darzy's idea of a rug to bring your space to life with some color and pattern. I'm also wondering if the TV could be moved to the spot under the heat pump? Alternately, could the TV go on the wall where your sofa currently is, then have the sofa where the two recliners currently are, and the recliners would go on the end facing the TV?

There is a window at the side of the room. 1930s Bungalow

I think, like you said, due to the fact that there's a larger space when it comes to the hotel lobbies is the reason as to why it works. I think that no matter what you put on the walls (whether it be concrete or marble) will result in tiles not working out. The industrial look tends to be exposed brickwork anyway, or cream or white colours so maybe that's an option you could look into. What did you end up doing?

I think you are wasting money . I'd leave the columns , do a couple of bi-fold aluminium doors , do a nice leather corner suite , and artwork , a Tv , make it more livable . I'd do a glass balustrade on the small stairs , 3 or 4 creeper type potplants and a couple of 'objects d'art' along the solid balustrade . Do you have another dining room ? If yes , make part of this an office/study ; if no , then a nice table and chairs . Right now , it looks unloved -- make it easier to fall in love with it , and you will !