K.L.
I have not used any of those sites to upload my picture for one main reason. Even if the hairstylist cuts my hair the same shape/style as int he picture, it won't look the exact same because my hair is a different texture and thickness than the sample photo. If the picture had my own face, then I would be severely disappointed that I didn't come out of the chair looking the same way. With a picture of a certain hairstyle on a different person, it is easier to comprehend that I don't look exactly like the photo. If you have the kind of hair that can do anything, then it might be a good choice for you though.
I always keep my hair shorter, even when I am not pregnant, but I definitely kept up with the cut more when I was pregnant because I could not stand having hair on my neck . . . way too hot! If you really like your longer hair, I would look up some fun updos that you can do to keep your hair off of your neck. I know there are lots of neat braids that you can learn to do.