I've been using a satin pillowcase by Betty Dain, that I purchased from Sally Beauty Supply store for $10.  I am in love with it.  I decided to switch to a satin pillowcase because my bonnet would always fall off during the night and I didn't like how flat my hair looked in the morning.  I tried using the pineapple method, but my hair is not really long enough to stay preserved over night with this method.  Ever since I started using my satin pillowcase, my wash-n-go, twist out, and braid out started to last longer and I did less fluffing of my hair the next morning.  What I love about sleeping on a satin pillowcase is my hair and skin are less dry because the satin material does not absorb oils like that other materials such as cotton.  Also, the satin creates a more smoother surface therefore my skin and hair receives less friction from tossing and turning during the night.  Less friction helps reduce hair breakage as well as reduce skin irritation due to acne.