Fleece of course is more of a winter fabric, but I have 5 kids with 4 of them in competitive sports, so there are a lot of sweat pants flying around this house lol!
Sweatshirts can be excellent pieces to repurpose and upcycle. My youngest boy is 8. He recently made a small throw pillow for his bed, out of his favorite yet too small sweatshirt. I helped him cut it out etc, helped him with the machine, but he did most of the work. He loves his GAP Hockey pillow!