Seems to me that with this being off the DR, it could serve as a place to have drinks before dinner or even dessert afterwards if you were entertaining. I am not sure I see the either/or proposition of everything clumped in the middle OR everything stuck in the corners. Without pix or a layout, it is hard to say for sure, but I would think a pair of chairs with a table between them, and perhaps an ottoman to share, could be placed by one window wall. You could then have a curved-back loveseat or small couch opposite that, floating in the room a bit, with a cocktail table in front of it, something perhaps with a glass top and iron legs to not take up a lot of visual space. Ideally I would think that you would want the entry to the DR open, not have it blocked by the loveseat, so the layout would work around that.

Keep the cats. Eliminate the clutter of books and odd shelving by building matching bookcases on the gabled end or ends for them. Full-height, or even IKEA Billys of various heights. But matching and covering the entire wall or walls. Clean out the files and get rid of any paperwork you don't absolutely have to keep. You might be able to move it all to document boxes on the shelves. Put the desk where the light from the skylights is best. Perpendicular to the wall under the skylights might work, facing the LR area and the windows. That puts the bookcase behind you for papers and references. For the "in the eaves" storage, haul it ALL out into the loft and vacuum the storage. Get rid of the stuff you were storing "just in case", outgrown clothing and tattered storage boxes. Rearrange things in there so the stuff you need most often is close to one of the hatches, and the once a year stuff is near another. All the holiday stuff, all the heavy clothing ... whatever. Put it back in labelled boxes. Instead of a sofa bed, consider an air-bed for guests. Bring in a comfy chair for reading, maybe placed near that railing so you can sit there and see out the windows and check on the rest of the house.

Go to a thrift shop and look for an attractive long, skinny leaning mirror, which will reflect light from your window and visually expand the room that way. Going by suggestions made in your other post, you hopefully will have gotten new bedding, moved the art lower, so that a mirror will reflect those updates. Also consider a swag lamp with white cord hanging over the bed--something cloudlike from Ikea like this to take advantage of your tall ceiling but bring it down a bit. This is the small Krusnig lampshade $13. Oops, sorry it won't link. You can find it here: https://www.ikea.com/us/en/catalog/products/00259914/ Consider a skyscape poster for over the bed to bring the outside inside and draw attention to the height of the room. If you're allowed to paint, paint the ceiling blue:

Please post a pic of the whole room. It might take several pics to show the room. You can do so in the comment section here. We are visual people so photos and a measured diagram showing dimensions help. Thank you for mentioning that it is a rental so we know right from the beginning that you aren't moving anything :)