Generally, sisters would make door decorations for individual new members, rather than the sorority doing the same type of decoration for everyone. All the sororities did their decorations this way - so there was lots of variety.
I shared my freshman-year dorm room with 2 other women. We were all in different sororities - the door looked like Greek alphabet soup
One of my roommates and I got cut-outs of our letters made from wrapping paper; my other roommate (a Theta) got a cut-out of a kite.