Ooh, tricky. Do you like the fabric aesthetically, i.e. would it please you to see it around your home? If so then maybe making it into cushion covers would be nice (pieced and/or patchworked if necessary — given the pinstripes, you could do fun things with placing the lines in different directions). If you don’t like it all that much (e.g. if you only had the trousers because you had to comply with a dress code), then cutting it up for stuffing might be your best bet.