Things I have foudn essential to have with me when traveling, especially because Im staying at super cheapie hotels:
Toilet paper*: oh the joys of shared bathrooms. Enough said.
Mid sized towel: works well for everyday as well as shower usage, and doesnt take up as much room in you luggage.
Small soap bar*
Shampoo, shower gel*
Shoes that double as slippers or shower shoes (such as crocs).
COURAGE to not be weirded out be creepy front desk men.
* = can be bought from any local convenience store if you dont want to carry them around.