Doing the laundry is a constant traveler's chore. Two general approaches:
1) Do the undies in the kitchen or bathroom sinks, and hang them up to dry wherever. Mix and match outer clothing, reusing as often as possible. All male readers know how bathrooms become obstacle courses.
2) Let the pros do it. Expensive in a hotel, but in BsAs there are lavanderias everywhere. U$5 for a bag of clothes. Only one problem:
In BsAs, the lavanderia often uses highly perfumed detergents. Highly. As in you smell like you spent the weekend in Madame Labonza's House of Heavenly Pleasure.
In fact, this makes me wonder if the House of HP is near my particular lavanderia, and if they use the same washing machines for my clothes!!
Hmm, maybe option 1) above may be the way to go.