My rule of thumb for Ellen Pompeo. If you can't walk with a train, then as far as I'm concerned, you're not allowed to wear a train. She ruined that dress by carrying it around like a 16 year old would, and that's a shame since the dress is beyond gorgeous.
LOVE Tilda's look, I think it's Haider Ackermann.
Michelle Pfeiffer's look leaves a bit to be desired. It's a beautiful dress, and she's gorgeous, but it lacks something.
ETA - Love Cate to death, but embroidered floral sprigs on a pregnant belly is not a good thing.