Here is an Afro-Asian theme to inspire you.

no pink. hurts your eyes.

Yes, please paint the hutch black and modernize it some by taking of the wavy front piece OR putting lights behind the waves and glam it a bit. How do you feel about DIY wall paper? You could host an after-hours salon decorating potluck party for all and anyone could bring to it some fun trinket to liven up the place. You, could pass out $10 off coupons to all those who attend.
Some ideas . . .

Here a really nice touch!

Just got an inspiration for your nail colors! Can you do a wall unit or shelving thing to hold your polish so that it'd decorate the wall but not take up floor space? You could simply have three l-o-n-g shelves across the hutch wall with track lights and mirror.

Keep the nice wood floor open! It's very nice. :)

I agree the pink needs to go. Customers want to come in and relax. Choose soothing colors to accent the black and white suggestions above. Go to IKEA and get some Billy cabinets with doors to hide supplies and open shelves to display merchandise. They even have lights you can mount inside to highlight your products. Get posters from manufacturers of the polishes you carry. Or better yet- hire a photographer to take pictures of your work. I think you need comfier chairs for the clients as well. Remember you are a business selling product and services. Keep the space professional, neat and relaxing and you will be successful.

500 years old? Early 1500s? I'm thinking you have a colonial or Victorian era building? And you want to keep the salon in sinc with that look . . . or not?

Anyway, LOVE the place. Here's some ideas that you could consider. The first idea is for pull-down tables so that your salon always looks neat and clean, well-organized, and fresh. Closet companies makes these; furniture places make these; and a DIY person could make these. You could also re-purpose armoires to do this. Also, if you wish to keep a theme from another era, you can use any number of techiniques to accomplish that. Hope you like.

Women like their distractions to be soothing, so check these ideas out.

Extra wall space behing the register?

This would be fun to do. Each station has it own drop-down table and chairs, drawers and cupboards.

Thanks for some great ideas to think about.

I think I would take the hutch out and add shelves along that whole wall. Add a couple of comfortable chairs and designate the window area as a reception area, with a rug. Reposition the nail tables...they can be staggered or turned parallel to the wall. It would be nice to have them match but I'm not sure what your budget is. I think some billowy white sheers would add some warmth. Perhaps some artwork? Decide if you like black or white as your main color and use the pink and green sparingly for accents. However, if you are looking to make big changes, you have to decide on a relaxing, comfortable space, fun, energetic space...it really depends on what you're looking to create.

Just found THIS and it's kind of what I thought would be a classy awesome concept for your salon stations.
http://www.yestertec.com/articles/carolina-loft