My Mother just made one for me last spring. What I ended up using was a Christmas pattern of all things. the three Kings robe is really nice as a cover up! I used embroidered (sp?) fabric with little gold thread through it and gold frog closers. It is still at my Mom's but I am thinking that it was a Simplicity pattern? Look in the back of the book under costumes.
I like cover ups that open in the front but there are other on the same pattern that are closed.
My mother is 83 and has been sewing since her teens, she said it was the easiest thing she ever made.
I used the one with the long pointed sleeves, very pretty!
Hope this helps!