I've read all of Aggie's books many times over, still do even though I know the plots/endings. Dorothy Sayers, if you haven't read her, she wasn't nearly as prolific as Aggie (I don't know that anybody was), not that many books but anybody who likes A.C. likes Dorothy's stories, they're good. Especially on howling-cold winter nights with hot toddies, hot chocolate, hot anything. (We've been way below zero with sporadic power outages here for several days.)
The 1930s-40s detective genre I love, too, Raymond Chandler, Dashiell Hammett, etc., not everybody's cup of tea but good detective mysteries.
full of all sorts of hard-boiled denizens.