I use old golf cart seats on all of my two person stands, they are comfortable to sit on, plus they will last forever. I use a SEM vinyl dye to camo them and a few leaves from the nearest oak tree. If you need pics, I will post some for you.
I use the square boat flotation throw cushions. They are made for the water so they dry out fast when they get wet and are light and have portable straps on them for carrying to the stand or tying it down. They don't cost much either they are $12 at Walmart. They come in duck camo. https://images-na.ssl-images-amazon.com/images/I/41dwDFu81VL.jpg