I was in the same situation regarding no bed in the spare bedroom. I bought several boxes and put them together to make a pretend bed, covered it with a duvet, put pillows and cushions where a headboard would've been, and it looked very convincing.
I used the boxes to store stuff from the cupboards - an estate agent friend gave me this tip: take about half the stuff out of your cupboards and store it away - even in paid-for storage if need be - then fling open your cupboards to prospective buyers to reveal them half empty. It gives the impression that you have loads of spare cupboard space. Buyers like that. Definitely a good idea if you are a hoarder, like me, and your cupboards are bursting at the seams.
Fresh flowers are always a nice touch. Also fresh fruit in a bowl. And it goes without saying, everything clean, uncluttered and nicely-smelling. Apologies if someone has already suggested any of this (I'm terrible for not reading all the thread).
Good luck if you do decide to sell up.