Long, gray hair makes a statement. Just look at the woman in this picture. She seems strong, confident and smart. Maybe the smart part is because of her glasses, but this is my point: how you look should be a reflection of who you are.
Makeup artist and style guru Bobbi Brown interviewed her hairstylist Mario Diab for her book for older women called "Living Beauty." In it, he suggests different haircuts based on your personality. If you pride yourself on your casual nature, consider a textured, short to medium haircut, he suggests. If you are classic and polished consider a one-length bob or a medium-length cut with a few face-framing layers. If you want versatility, keep hair longer but add bangs.
Also consider your hair texture and face shape. The woman in this picture obviously has thick hair, which is why it looks good longer. If your hair is thin and you have precious little of it, you'll want to go shorter so you have body. Get layers cut in. When it comes to face shapes, there are all sorts of fun rules to consider.
Check out Haircuts: Best Haircuts for Every Face Shape.