Remember that hair grows forever, it doesn't stop. If you go out on a limb, drastically change your hairstyle and end up hating it, it can always be changed to something else, another style or color. Talk to your stylist to see if they have any fun celebrity hairstyles for you. You never know, they may have a style that they have been dying to try on you, but never had the opportunity before. Most hairdressers won't try to push a new style on you (nor should they), but if you ask, they love to share their creative side.
Celebrities and magazines are a great source of finding a hairstyle for long hair as many celebrities change their style regularly. If you are looking for a new style which is in fashion and trendy, watching what the celebrities are doing with their hair on the red carpet is a perfect way to do this.