Strapless Wedding Guest Dresses & Windsor Strapless Wedding Dresses With Black Long Black Wedding Guest Dresses Strapless Black Velvet Gown With Bow Accent on Luulla 34 Best Long Sleeve Wedding Guest Dresses of 2021 Long Strapless Dresses & Windsor. The Black Strapless Notched Velvet Long Wedding Guest Dress combines luxurious velvet fabric with a sleek strapless design for a sophisticated evening look. The subtle notched detail adds a modern edge, while the floor length silhouette ensures elegance and poise. This dress offers a perfect balance of comfort and style, making it an excellent choice for guests attending formal weddings or upscale events.