I used to not bother straightening my hair every morning, but when I'd sleep funny, my hair would end up stickin' out all over and people started making fun of me. I finally gave in and now I always straighten my hair before I leave the house. I mean, I don't actually comb it or anything because that's waaaay too much trouble. I just flatted out the frizzy spots.
I think both look fine. Do whatever one makes you happy. If your happy with your hair wavy then keep it that way. If your willing to go through the extra work of getting up to straighten it then you can do that too. It really depends on your feelings and how much you like your natural hair.