Despite having a hardscrabble farmer and an avowed socialist in their ranks, the incoming class of senators does little to shake the Senate's image as a millionaires' club. Bob Corker, senator-elect from Tennessee, boasts an estimated $64 million to $236 million fortune, according to the financial disclosure he filed to the Senate. Claire McCaskill, the senator-to-be from Missouri, has a portfolio worth roughly $13 million to $29 million. And Sheldon Whitehouse, who ousted the fifth-richest member of the Senate, Lincoln Chaffee of Rhode Island, is hardly hurting for cash himself: He has $4 million to $14 million parked in various...