While of course people will judge others based on appearance, hairstyle is a personal choice. I think whatever keeps your hair under control, especially based on what you are doing, is fine. I would stay away from high pigtails (very toddler), but tying your hair back in braids is perfectly acceptable, in my book. Hair changes, "in" style changes, whatever .. wear what's comfortable for you
I have been known to wear low pigtails (gathered behind the ears, resting on my shoulders) for dance lessons or yoga class (keeps hair out of my face, and I can still lay flat on my back at the end of yoga class). I usually do not wear my hair up, as I like the way it frames my face when down. I do recall one incident when I was at a charity banquet with my parents, sister, and some other relatives. Teens were serving coffee and went around our table asking the adults if they'd like some, and moved on without asking me. I commented on this and my dad said, "Maybe if you cut your hair and look your age.." I picked up my jaw from the floor and flagged down the next teen with a coffee pot to ask for some. (Mind you, my hair is not even mid-back, just to shoulder-blade length, and I'd worn it down that eve, with a little mousse to control my natural curls, so I thought I looked plenty grown-up enough for coffee! I was 25ish at the time.)
On another note, I had pretty straight hair, with a slight wave, until my daughter was born and my hair suddenly has tons of natural curl. I fought it with a straightener for a good 4 years before learning how to manage the curl and now I love it! With changes in what our hair WILL do, sometimes we have to adapt our personal style.
SiotehCat, I envy you your long hair! My mother had 2 girls and kept our hair chin-length growing up for easier care. I grew mine out after high school, and it's never gotten longer than it is now. I'd love to have waist-length!
yokozbornak -- your comment about your friend with ever-changing haircolour reminds me of a dance instructor I know who's long and lean with short black hair and she often has streaks of colour in it .. blue, purple, red, pink (probably did green for St. Patrick's day, haven't seen her this week haha). She's got the lively personality to go with the hair and it really works on her. She and the studio owner have similar builds and, both 40+, can really rock the backless tops, miniskirts and 3" heeled dance shoes at showcases too!