Medium hairstyles, like that which Elizabeth Banks has, can still be worn in a formal updo as there is enough length to do so. She has lots of lift off the scalp which makes this elegant style even more exquisite.

Charlize Theron at the Paris Premiere of "The Burning Plan".
Medium long hair may think that it is too short to be done in a formal updo, however, consider the alternative of a low-riding gathering like this one on Charlize Theron. You can curl the front section or sections into ringlets or opt to leave them straight as is demonstrated here.

Brittany Curran wearing a prom updo dark brown hairstyle while attending the World Premiere of “Ace Ventura Jr: Pet Detective” held at Springs Preserve. Las Vegas, Nevada. USA. 2009.

Amber Heard is wearing her hair in a sexy romantic updo hairstyle while attending the Art of Elysium 2nd Annual Heaven Gala held at The Vibiana.
Los Angeles, California. This hairstyle is perfect as a prom hairstyle, wedding hairstyle or in general a elegant hairstyle

Vanessa Hudgens at the the 81st Annual Academy Awards - Vanity Fair Party, Hollywood, California.

Penelope Cruz at the Orange British Academy Film Awards 2009.

Denise Richards is having a bad hair day while attending the 2006 Billboard Music Awards, at the MGM Grand Garden Arena, Las Vegas, Nevada.
This hairstyle is just, well too much! She would look much better in a high updo hairstyle with a sleeker look than having her hair look like someone tried to weave a bowl out of it!

Julie Benz is wearing her hair in a elegant updo hairstyle while attending the 15th Annual Screen Actors Guild Awards.

Beyonce is wearing her hair in a elegant high updo hairstyle while attending the 2008 Kennedy Center Honors in Washington DC.
Beyonce is wearing a very elegant high updo hairstyle. While this hairstyle almost looks just short of a beehive it is still very gorgeous and elegant. This hairstyle is perfect for any elegant occasion and would very much be considered a wedding hairstyle, or a prom hairstyle.

Zooey Deschanel is wearing her hair in a high updo hairstyle while attending the New York premiere of the new film ‘The Day The Earth Stood Still’ held at the AMC Loews Lincoln Square Theatre, NYC.
This hairstyle is a bit messy but looks great! Zooey Deschanel’s bangs also look great as they are framing her face. I definitely recommend this as a wedding hairstyle, prom hairstyle or elegant hairstyle.