Mr. Fashion,
As you say... it is easier to be a critic than a producer ... but these are your viewers telling you! You have access to the girls - they do not.
Here's some ideas:
TWO GIRLS WORKING WITH EACH OTHER!
They can shampoo, brush, touch, oil, smell...
MAKING HAIRSTYLES AND LETTING THEM FALL
Show the girl making a giant bun on her head and show it.
Nothing is more sexy than seeing a pile of hair on a woman's head just waiting to fall.
POSING
Think of a woman's long hair as a waterfall... it will cascade down from her head along her shoulder, falling over the side of her chair, maybe on to a table to the floor.
She can get up from the chair, move to a pillow, spread out her hair again.
One of my favorite poses would be to see a woman reclining in a chair: her hair falls COMPLETELY FREE, straight down from her head touching nothing else
Just three quick ideas that celebrate the beauty of your models' hair:
no kissing, no nudity, no sex... just ART!