Whenever I stay at hotels that offer shower caps as an amenity, I grab them. They weigh virtually nothing and take up no room. There are many travel uses for shower caps but here are a few besides the obvious use of a cap when showering:
Shoe covers. Cover your shoes with them to protect everything else in your bag.
Electronics covers. Okay, this only works for smaller items but they work well.
Makeup wrap. While they are not waterproof or even leak proof, shower caps are still helpful to wrap up makeup items to prevent contact with clothing.
Food wrap. Easy way to keep all your food like snack bars in one place.
General organizer. For example, one can be used for business cards, another for presentation materials, and a third one for jewelry.
Of course, shower caps don’t last forever and not all hotels offer this amenity. That’s why I said at the top that I grab them whenever possible. They can be one of your best travel companions.