Unfortunately neither my wife nor I remember the manufacturer of the replacement vinyl window. The original wood windows were Weathershield wood windows; probably a builders grade. The Marvin representative gave us a price of $5700 for a new bay window with double hung windows since my wife no longer wants a bow. He also quoted us a price of $3600 for a flat from window with double hungs. Based on what you have said and other threads in this forum my guess is that most bays or bows will be in the $5700 + range. I think the flat window will be the winner from whoever gives us the best price. The Marvin representative noticed that the window tipped forward slightly. I now remember that the vinyl replacement window was for 2 x 4 construction while our house is 2 x 6. We weren't told of this "error" until our wood window was out. The company we bought the window from assured us that size mismatch would not present a problem. The Marvin representative said that was not necessarily the case.

If you remove the bay window, the head and seat board, and the exterior "roof over the window"," you will have a flat rough opening. You can work with that but it sounds like you want to shorten the width. Are you also changing the siding? How much work would it be to make the window centered? Pretty straightforward except you are going to have to patch the siding together if you aren't changing it. Also, it looks more like a bow (6" radius =/-) rather than a bay (30 or 45 degree).

IMO post the new plan . Maybe the guest would like a door to the outside. Then oyu just replace that bay with a sliding patio door or french doos which ever works with the exterior . I also love the box window look but really we need to see the xterior of the house and aflooor plan of thenew and old spaces together.

Hi, Texan here, too. :) What I’d do in this room: A curtain rod that spans the width of the window wall, with art on each side wall. Terrible mock-ups, but hard for me to do a good one from an angle. I don’t know your decor style, or measurements, so am just showing the idea … not suggesting these specific items. Whatever shape table you decide, it might work/look better to lay the rug vertically, as well as the table (unless you do a round one). You’ll need to show more angles of the room for more suggestions on placement. I definitely wouldn’t sink a lot money into someone else’s house and I wouldn’t try to cheesy fake that there are windows there — curtains all the way around, mirrors, etc. You could embrace it and make it a cool art nook. ETA: Another idea, if you’re a handy DIYer, is a bench built-in. You’d just have the one window, yes, but again, could do art on the side walls, and have pillows. If you’re handy, it shouldn’t be a huge investment, or you could use bench seating that’s not built-in. Just depends on your needs.