While I try varying them to suit the question, my favourite related texts to use are 'The Hound Of The Baskervilles' (As an example of 'Traditional' CF, and there's a very good line describing Holmes that encapulates the singlemindedness of the 'Traditional' detective. His ignorance is as extraordinary as his knowledge), 'Out Of The Past' (Another film noir. It is a very good example of the 'criminal underworld' element of this genre as the story is a binary opposition between a 'Middle America' and a dominantly Hispanic and African-American 'underworld' [Which is interesting in comparison to Snow Falling On Cedar's plea to refrain from bigotry]) and 'The Mousetrap' (Works both as 'Traditional' and because it was a source of 'inspiration' for 'The Real Inspector Hound'. It's because it's crazy that it's dangerous..) Hopefully we get a question that these work well with.
Also go with the name-dropping sometimes for current CF, mentioning stuff like 'Silent Witness'. (My evaluation of CF is strongly influenced by context, the genre continually evolving from Traditional to Modern (The Big Sleep) to Post-Modern, reflected in changing textual aspects as multi-genericism (Going from Traditional generally focusing upon the crime and it's resolution, to Modern CF's emphasis upon romantic elements, as seen in The Big Sleep, where Marlowe and Vivian are shown together at the beginning and end, the crime happening between, on to SFOC, with about eight different genres pollinating into a 'Post-Modern' Crime Fiction..) Something like that at least.
EDIT-I need to go over my notes again, as can probably be seen in the confused, web-like structure of this rambling. (Ironically mirroring that of many CF texts.)