I personally prefer A- line dresses for lunch dates and body con dresses for dinner, as a well-fitted dress is sexier and best suited for the night. Tulip hem , pephem and skater shapes are softer, feminine and perfect for brunch or lunch as it adds a bit of innocence to the entire look, which is perfect for Valentine's day. Think tutu skirts and full volume circle skirts and you're set.
Oh and by the way, Happy Valentine's day to you. I love you!