Laundry - an ongoing problem for travelers.
Keep all your old knickers and bras. Instead of washing them in your hotel room just throw them away each day. Or you can sometimes pick up a multi pack from Dept. stores. Picked up 12 pairs for $8 at Target recently.
Most hotels with laundry facilities have large washing machines available with detergent $1 a cup. If not doing 'undies' two could share a load.
If you like to sleep 'in the raw' please dont as you will be sharing a room !