I was a bridesmaid in two weddings last year. For the first, we had a choice of about 10 different styles in one collection...the only requirement was that it had to be lavendar and we needed grey or silver shoes. Two of us went with short sleeves, three had sleeveless and one went strapless...we all went with the dress we felt most comfortable wearing. There were six bridesmaids with a wide range of body types and I can't think of any style that would have flattered all of us. I know there's no way in hell I could have pulled off strapless!
For the second, we went with separates. We were all going to wear the same skirt and have a choice of tops. It just so happened that we all liked the same top.
(also had sleeves) I've worn that dress several times since the wedding...comes in handy for Jaycee banquets!
If someone's that insecure that she thinks the only way she'll look pretty at her wedding is if the rest of the bridal party looks hideous, that's sad.