A white wedding gown is great, not only is it traditional and you have about 3 billion options when you pick one out, but it insures you that you will be the only gal in white! But this tradition isn't as old as you would think...
In fact, Queen Victoria of Scots popularized the white wedding gown in 1840 when she married Albert of Saxe. And the color white was chosen as a sign of wealth and high social status, not associated with innocence (girls, you are off the hook). Even with the Queen's choice, women around the Western world still wore wedding dresses in a variety of colors and styles, and they could be any color except black/red (indicating mourning/prostitutes). It wasn't until the 1950's where American brides started wearing almost all white, in the fashion of Hollywood and royalty...thank god for wikipedia.
Also, look for more lessons on marriage traditions throughout the week, you are going to seem super smart (or really lame) when you can mention these fun facts at your friends' weddings!
Now onto the dresses! How about a little gray? I have never seen a bride that I know pick anything but white (not even ivory, now that I think about it), but that's not saying they can't be beautiful and breathtaking, too! And now that you know the wiki version of the tradition, maybe you won't feel so bad breaking it!