I have been to weddings where the matron of honor wears a different dress, even a different color than the bridesmaids. It has always been the contrasting color, which looks nice imo.
Honestly however, it does come down to what your sis wants I think, I have been in 4 weddings and NEVER worn any of my dresses again. They hang in my closet...close to $950 worth of very pretty one occasion dresses, just hanging there.
I hope you get a good resolution Kat!
I'm sure you will look beautiful in whatever she chooses.
