Beau suggests someone devilishly handsome, with a large measure of southern charm--a nice image to bestow on your boy. Often solely a nickname in the past, it's now standing firmly on its own--this year ranking at Number 311. Beau has been on the Social Security list non-stop since 1967, reaching a high of Number 203 in 1980.
Beau also has something of a dapper image, thanks to the fashionable Beau Brummell (born George), which led to the stylish New York mayor Jimmy Walker being called Beau James. Other notable Beaus had more formal names at birth--Beaus Bridges and Biden were both the third sons in their families to carry their fathers' names--Lloyd Vernet Bridges III and Joseph Robinette Biden III.
The novel Beau Geste was a major bestseller in its day and was also a popular movie--in that case Michael was the character's birth name, and many will remember that the child of Ashley and Melanie Wilkes in Gone With the Wind was called Beau, and there was also a Beau on the old TV western Maverick.
And if you want a more substantial name on the birth certificate, try Beauregard.
Art Garfunkel, Emma Bunton, Wendy Wilson, and now Jamie-Lynn Sigler all have sons named Beau.