Suits You, Sarah

 is a free quest in Fallout: New Vegas, given to the Courier by Sarah Weintraub.

Detailed walkthrough
After following the right dialogue tree, the player will be able to bring Vault jumpsuits to Sarah, which will result in caps, Strip reputation, and a discounted stay. She does not accept armored vault suits, utility vault suits, or suits bought (or stolen) from her store. But she will accept them stolen from the guest rooms in Vault 21. With a barter check of 65, she will accept Boomer jumpsuits.

After bringing her about 30 Vault suits, upon revisiting her she'll mention missing the player character. You will then be able to have sex with her as you both "catch up" with one another, which gives the "well-rested" bonus (which is normally absent from the hotel room beds she offers). Also, after 2 speech checks, 50 and 70 respectively, she will agree to having sex after receiving suits, along with accepting Boomer suits.

You have to go to your room (which is the room left to Sarah's room) after work hours and she teleports to your room immediately. If you also put a sexy sleepwear in her inventory, she wears it for you. If you remove her vault 21 jumpsuit while she is still sleeping she will put on whatever you put in her inventory but won't remove it again.

Bugs

 * Weintraub does not accept Vault 3 utility jumpsuits.