I can't say its the "best" amenity, but the Hyatt Dulles has a nice selection...

Cookies Turndown
Fresh baked cookies with a carafe of ice cold milk

Cheese & Wine
Boursin cheese served with an assortment of crackers and your choice of red or white wine

Dry Snack Attack
Assorted trail mix and mixed nuts served with locally brewed Dominion's Ale & Lager

Healthy Flight
Seasonal whole fruit served in an oversized martini glass accompanied by individual fruit juices

Jetlag Refresh
A selection of fresh vegetables served with dip, complimented with mineral water

First Class to Santa Fe
Tortilla chips and a spicy salsa paired with ice cold coronas

A little something for everyones taste.