I think the DSW chairs would look great but I agree they seem to be everywhere now so it's hard to justify the price tag for something which isn't very unique (and essentially just plastic). You mentioned mid century. Have you considered auctions/gumtree. You can pick up a set of original mid century chairs very cheaply if you hunt for them. I'm on the look out too for dining chairs and have also found most chairs I like cost £150+.

Greys and browns can be difficult to mix colourwise as one is warm the other is cold. however, It's not impossible. I would suggest that you try marrying the wooden furniture with the colour on the walls, therefore going for a grey chair but with good warm wooden legs. I found an exact match in design to the chair that you like, however the covering is grey, but the darker oak legs will gel well with your lovely wooden furntiure.Link below for shopping:- shopping link to chairs

Haven't you "had a poll" featuring the pink chairs before? I guess you might need a different marketing strategy if the polls aren't working......

I don’t think a wishbone chair will work size wise, it’s quite a big chair and I dont think I’ve seen a table that the backrest of the chair sits under so they need to sit away from the table (where they look best too and you always see at least one on an angle as i have lol!) The Vitra Belleville could work oictured below? I also really like the Hay suggestion, you could look at their others too, and your Eames suggestion would also work well. i have all metal tolix and they are cold and uncomfy but you could go for the wood option as Wumi said and add a sheepskin pad if needed or you can get leather seat pads that screw in.