Advanced higher english dissertation - arthur miller plays?

the things to be about 4000 words (i think) and im wanting to do it on 2/3 arthur miller plays, but the only one i know is the crucible, had a flick through all my sons too though which looks intresting. anyhoo, i just need a common thread between a couple of his plays as comparision seems to be the nature of the thing. also if you can think of anybody else who has done a few plays which have some common threads, im all ears. ta!