For most of my life, I've always had long hair. A few times I'd cut it short, but it can be stubborn and unruly, and it's just easier to manage when longer. Plus, I really like it better that way.
When it's wet, it's about to my bra line. I'll probably let it grow 2-4 more inches and keep it there. That may take a while because despite growing fast, my hair gets dry and frizzy, so I have it trimmed just a little every 4-5 weeks.
I'm 50, by the way. I don't believe in old notions that say a woman has to cut her hair or dress in a matronly fashion once she hits a certain age.
Do what's best for you, what works for your hair type, and what makes you feel good. If you don't already have one, find a really good stylist who will meet with you first for a consultation before cutting! Bring pictures of styles you like and he/she can help determine which will work best with your hair to give you the results you want. Have him/her show you how to style it when you're home doing it yourself.
Good luck and hope you find a style that makes you happy!