I didn't find out with DD.. the whole time I hoped for and expected a boy. Not knowing made the whole pregnancy really exciting. For that reason, I intend to never find out the sex of any future babies.
To be honest though, during the labour (10hrs and no pain relief) the sex of my baby was the last thing on my mind, and when DH finally said "It's a girl" I felt no real reaction, just "oh".. mainly just felt relieved and shocked that labour was finally over!
But, not expecting a girl made me love having a girl. I felt so proud of her, surprising us like that, and also looking so cute and pretty..