I've used silk and satin pillowcases for years.  They're so much better for your hair and you don't wake up with "pillow face".

I got the king size and they fit my king pillows perfectly.  They're envelope type but are big enough that your pillow won't come out as you're tossing and turning and you won't have to fight to get the pillow in.

I found them cool to sleep on and they feel lovely.  I wash all my linens when I buy them and these came out perfectly done on a cool wash and air dried.