This from Jayplay.
“A decent amount of people” seems fitting on Halloween, but I’d use “number of people” instead. Here’s why:
Amount and number work in much the same way as less and fewer.
That is, amount generally applies to things we consider as a whole:
Kyle always adds equal amounts of hot sauce and ketchup to his ice cream. Or, You’ve done a fair amount of work on your earwax collection, haven’t you?
Number generally applies to things we consider individually:
I can’t believe the number of people wearing tutus for Halloween this year. Or, The number of widgets the factory produces has increased dramatically since the werewolf became foreman.
Random House, in a usage note, calls this the “traditional distinction” but then shrugs it off and sanctions the use of “amount of people” basically because some people use it that way in speech and writing. American Heritage seems agnostic.
I agree with Random House that “amount of people” can be correct, especially on Halloween. The movie Night of the Living Dead comes to mind. In that movie, a ghastly number of zombies consume a large amount of townspeople.
I don’t condone cannibalism, so I’d suggest using number of people.
That will give you something to chew on over the weekend.