In preparation for my parents' visit, we simplified the room, moved the bed away from the window-wall, hung some blackout curtains and just tidied up.
Now it's looking much more guest friendly! It still serves as my sewing room, but I packed my sewing table away and stored it in our big storage room to make room for their stay.
My eventual goal is to DIY a simple headboard for the bed, or hang some artwork (we still have that branch metal piece that used to hang in our master bed room, and we've been playing with the idea of hanging that here temporarily too).
But in the meantime, we like that there's plenty of space for guests, plenty of privacy (it's on the left wing of the house all by itself), and is cozy, simple and functional.