We brought out stuffed animals after a while, but this old squishy/squeaky Santa (which was mine as a kid) was all he really wanted. He loved setting it up then aiming for it as he jumped, making it squeak as he landed on it.
I realized that he really wanted more height, so I pulled up a chair for him. I think he would have been much happier if we turned the living room chair around so he could jump off of the back of it, but I didn't think of it until it was too late. Next time!
While my husband and I jumped in too from time to time, after a while he wanted us to jump alongside him. Fun!