Obviously you should do what you want and take advantage of your good fortune, but here's what comes to mind to start.

-Have her use her hair anywhere and everywhere on your body. Her hair is long enough for her to straddle you or be next to you, grab the last few inches with her fingers, and use them as a brush. She can also just use her entire mane on your body. The result is an amazing sensory overload whether combined with or separate from sex. You may also be able to use her own hair on her to some effect.

-If you are into her breasts, use her hair as lingerie. Have her cover her body with her hair, and then you or she can push it back to reveal her body. If she makes it beyond classic length, she can cover her entire body with hair.

-Have her put her hair up in a bun, have sex with her on top, and have her release it to tumble down just as you are about to finish.

-Plain old missionary-style can be great with very long hair fanned out behind her head, because that's where your face will be.

-If you like something to pull, braided pigtails.

- Make sure that once in a while, have sex without involving her hair. Have her hair pulled back in a braid, or up in a bun. This is easier if she braids her hair at night anyway, because sometimes you just won't take the time to let it down. And she should probably be braiding her hair at night anyway to avoid damage.

If at all possible, learn to brush, braid, and put up her hair, and help her whenever possible. It's very intimate and shows you care and recognize how much work such long hair is. Be gentle with her hair; have fun, but recognize how delicate it is.

Finally, like everyone else says, take pictures if at all possible. Someday she will either be gone ( ) or will decide it's time to cut her hair. That can be either terrifying or exciting, but either way you'll want the memories.