Evelyn, a soft and feminine name hugely popular a hundred years ago (it was Number 12 in the 1910s), is returning to favor in a big way now. We predict that in the next decade Evelyn will achieve its former heights, joining a legion of contemporary little Evas, Avas, Eves, Evies, and Evelines. In 2009, Evelyn rose 15 places to breach the Top 40 for the first time since 1939!--and in 2011 leaped even further to Number 24.
While Evelyn is a lovely name, its problem is its similarity to so many other stylish names these days, so your little Evelyn will seem less distinctive given how many other popular names there are that start with Ev or Av, from Eva to Avery, and end with Lyn: Brooklyn, Caitlin et al.
Originally a masculine name, its most famous bearer is writer Evelyn Waugh. (Trivia note: Evelyn Waugh was married to a woman named Evelyn, and they were known as 'He-Evelyn" and "She-Evelyn'.) Its quiet persona was reversed with the character Evelyn Salt, played by Angelina Jolie.
Your great-aunt, and despite the fact that writer Evelyn Waugh was male, not your baby boy.