Call for help...

I have an early May evening wedding in New York - the dress is "festive" - dark suit or tux for men. I have been on the hunt for my dress/gown.

I like this from Neiman Marcus

I like this from Vera Wang

and I like this from Calvin Klein

but none have me thrilled to a point of absolute certainty.

Do you think it is an absolute must to wear a long gown? It is a small evening wedding of about 80 and the reception is at St. Bartholomew's Cafe.

If I can short - I like this dress from Nordstroms.

Where do you like to shop for formal wear? I need suggestions where to look!