How Long?
Conventional wisdom has it that a resume should be one page and although brief is good, I think it is dangerous to try it force anything. The resume should be as long as it needs to be to convey your value. There was a story of a ancient innkeeper named Procrustes whose beds were only one size. If a guest was too tall for the bed, he would chop their legs; if they were too short he would stretch them. Don’t do the same to your resume, it seldom works out.
Of course if you are an academic, where resumes are more likely called Curriculum Vitae (someday someone will come up with an English word for resume) then longer is better — which, if you have ever had to buy sheets for a college student, explains is why beds in college dorms tend to be longer.