Anonymous wrote:Black tie means floor length. Black tie is not a cocktail dress. You would wear a cocktail dress to a wedding that is not black tie.
Cocktail dress is fine for black tie as long as it is very dressy. Especially, if it is "black tie optional."
White tie requires a formal dress.
The last wedding we went to was at 5 and was black tie optional. DH refused to wear his tux over my protest. He was right. The groomsmen were the only ones in tux except for a handful of others.
I think a lot depends on the time of the wedding.
OP, what time is the wedding?