Portable laundry bins!

like these

I have seen some really pretty journals at like Hobby Lobby and Steinmart that would be a good gift they could use it to journal about their project and stay in your town etc. maybe it would encourage them to actually keep a journal rather than just go digital.
The toiletry kit would be good, I think I would stay away from anything that requires sizes like the shower shoes. EOS lip balm is a great gift too I love the stuff. I have made up little kits with wet wipes, purel hand sanitizer, EOS, and a little sunscreen/lotion and put them inside a cute cap and bundled it up and tied it with a piece of ribbon. It makes a cute gift and it's all useful. The cap can be something from your area or something cute, they can wear the caps to work and they are adjustable.

Oh another thing I love and have in my rv when we travel so I can carry it to shower rooms if need be is a mesh shower caddy you can put all your stuff in it carry it with you and water just goes through it. You could add some goodies in the caddy.

http://www.bedbathandbeyond.com/store/s/mesh-shower-caddy?ta=typeahead

I wouldn't use products, though Ravencajun's sound good, and if they're working outside the sun protection might be very welcome. It's just very personal and you don't know who has allergies and sensitivities. Having to say no thank-you and give the products away can be disheartening, when the point of the gift is the opposite.

You didn't mention a price range. Awhile back I did something a little similar, but it was only for six girls and I had a high budget. They LOVED it! It was inexpensive train case style organizers with the tacklebox style trays that lift/hinge out, with a few little things inside. Each got a thumb drive, cute ball speaker for the iPod/phone, pretty pencil, goofy animal notepad, a cute keychain and a screen cleaning cloth. I think they cost about $60 each to put together, but you could keep it under $40 and still put a few little things inside, or you could do under $15 just with a thumb drive, pocket notepad, etc.

Another very popular such gift was Leathman micras. Those are around $20.

Going back to Ravencajun's suggestion, if they'll be working outside, there are cute (like young cute) full on sunhats which protect the neck as well as the face for less than $10.

Still, I like your own idea of the hair wrap and shower shoes, especially those superabsorbancy towels that fold to nothing. Even if they already have shower shoes, those get gross and need replacing. The only thing would be knowing the right sizes. You could add a few spa items like a small loofah and a pretty emery board.

Hand cream is good along with tube of hand sanitizer (not the liquid) , small packs of Kleenex' small 3x5 note pads, sticky notes, pens, pencils, stamps, picture post cards, small pen type flashlight, and check out items in the camping dept such as mirrors, waterless soap, and wipes.

What about the cups/glasses with the screw on lids and a straw. Those seem to be popular.