Hangers, Woolite, Shout, white tissue paper, Fabreze and sewing kit.

It sounds like the way Eloise at the Plaza would have packed, these things are essential. You need these items to maintain your costumes on a long (often dirty) tour.  And trust BDC, you cannot depend upon a theater anywhere in the world to provide plastic hangers.   Wrapping damp costumes in white tissue paper can mitigate the ill effects of packing after a show; and Fabreze can render a garment wearable even if there was no time to wash it between shows.

Here’s a special secret for costume-heavy productions:  Find out if you can keep costumes hanging up to dry overnight in the dressing room of your theater after the performance (if you aren’t leaving on a 7 a.m. flight the next morning!).

This way, you or the stage manager or delegated dancer can return to the theater and pack DRY costumes for your next show rather than throwing sweaty costumes into a case and digging through the moist malodorous garments upon arrival at your next destination.  

If the dressing rooms are not an option, try to convince your dancers (or actors) to be responsible for their own costumes and hang them in the shower over night.   Another interesting option: get some large standing fans and direct them at the costumes on a rack during the performance -- as the dancers come off stage and change, instead of hurling the wet stuff into a corner, hang them up and blow them dry!  

Once, in Trivandrum, India, where it was at least 95 degrees on stage, BDC were allowed to hang our costumes to dry overnight.  There was no garment rack per se, so the company tech director rigged a rope between two walls of the dressing room and all of the sweaty costumes were hanging there.  

The next morning, the company was horrified to find the entire bunch of costumes in a disgusting pile on the floor:  the rope had broken and everything fell together on the filthy floor.  UGH!