Creating a story-collection-a-day list for October prompted another list. Here's a novella a day for October (plus one for a later holiday). A broader scope than most short stories, but more focused than a novel, some critics have said the novella is the best length for creating a sustained chill. Some of these novellas are more than one thing, so you'll see an overlap in the numbers below.
1-5: Gothic-y
5-11: Ghostly
11-14: Fangs a lot
14-17: Keep Watching the Skies!
16-20: Frosty
19-23: Nature abhors ... us
21-23: Folksy
20-31: Changeable reality
31: Bradbury-ish
32: Hohoho!
Most of these are novellas according to isfdb.com. They deem one a novelette but it won a World Fantasy award as best novella, which may indicate how fluid the designation can be. Another is tagged as a novel, but if so, it's a really, really short novel.
Whatever the length, I would call all of these good reads.
