Here are a few comments from Vera Wang:

“The shape of the skirt is what determines the look and movement of your wedding
dress. There are a few key shapes to choose from: Make a grand impression with a
full, gathered skirt or elongate your silhouette with a classic A-line. If you
are tall and thin, a circular skirt can be incredibly graceful particularly in a
chiffon fabric. If you are curvy, a mermaid shape is extremely flattering but
may need a cover-up during more conservative moments such as the ceremony.
Finally, I highly recommend a narrow column for a skirt shape that is a
sophisticated alternative to a full gown. A floor-length sheath is a nod to
eveningwear and is considered quite avant-garde for a wedding dress.”