I'm not going to make a suggestion on the decorations here, just a suggestion on how to accommodate the suggestions. You might look into doing a green-screen set up which would let you insert whatever background images you want in post-production. You could then pull suggestions from Patreon supporters out of a hat and, assuming the suggestion is acceptable, have that as the background for one episode. That would give a wider selection of people a chance to "win", and it would be an ongoing thing rather than a one-off. One way of doing it would be to provide a gallery of photos and let each person either select one or provide one of his own.
I've no experience doing green-screen stuff myself, but there are a couple of Youtube channels I watch which use it, so it can't be too exotic in terms of software.