at, at about, at all

At is a preposition and requires an object. One should not ask "Where are you staying at?" but "What motel are you staying at?" or, better,"At what motel are you staying?" At is unnecessary in expressions such as at about and at around (See about). At all, meaning "to the slightest degree," is nonstandard when used in a statement such as "They were thoughtless at all." When used to mean "wholly" or "completely," at all should be replaced by of all: "Sue is the finest girl of all."