From Los Gatos Black on Halloween by Marisa Montes; illustrated by Yuyi Morales (Henry Holt, 2006):
Los gatos black with eyes of green,
Cats slink and creep on Halloween.
With ojos keen that squint and gleam--
They yowl, they hiss...they sometimes scream.
This book won the 2008 Pura Belpre Medal for Yuyi Morales's richly atmospheric paintings, which reflect the traditions of both Halloween and the Mexican Day of the Dead. It also won a Pura Belpre Honor for Marisa Montes's rhyming text about a monster's ball on Halloween night that is interrupted by the arrival of [spoiler alert!] trick-or-treaters.
Montes incorporates some spooky Spanish words: see above as well as, for example, la bruja (witch), el esqueleto (skeleton), la calabaza (pumpkin), and medianoche (midnight). I like that the Spanish words are specific to the Halloween context; this helps integrate them into the text. The text itself is sometimes redundant (I don't think the English word is always required, especially when there are context clues, illustrations, and a glossary), but that doesn't seem to bother the kids.
What does bother them are those gorgeous, glowing paintings. Too scary! Maybe next year.