Mikaela Shiffrin's Must Haves Include a Pair of Cool-Kid Sneakers She's Loved Since Age 9

Shiffrin has silk pillowcases stashed everywhere — at her boyfriend Aleksander Aamodt Kilde's apartment in Europe, at home, and in her travel bag. She loves this Slip Silk Pillowcase in Navy ($89) as well as the ones by Blissy, though she's not picky. "I just love them for skin and hair," she says. Plus, when you're traveling, you rely a lot on other people to keep spaces clean. For Shiffrin, having her own pillow can bring a little more peace of mind.

Pro Tip: If you're going to travel with your own pillowcase like Shiffrin, don't opt for white. "I need to have a colorful pillowcase when I'm traveling, so I don't forget it at hotels," she says. Her favorite is a dark blue.