You can order up to three swatches for free. That way you can feel the fabric for yourself.

https://www.westelm.com/products/swatches/?searchredir=true&cm_sp=HeaderLinks--OnsiteSearch--MainSite&cm_type=OnsiteSearch&term=swatch&searchredirtype=co

Typically the more man-made materials in the content the more scratchy the feel. 100% Olefin is probably the worst offender. Natural fabrics such as cotton, wool and linen will be softer (but always more expensive). Get a sample and here's a Pro Tip : Instead of touching with your fingers, hold it up to your cheek, that will tell you how comfortable the material will be.