Bruno Mars is among the flashiest, most versatile singer/songwriters in post-millennial pop. An all-around entertainer, he also plays multiple instruments, produces, and choreographs. His path to mainstream success was lengthy. After he worked a string of behind-the-scenes jobs, including writing songs for Brandy, singing backup for Sugababes, and impersonating Elvis Presley, he put his name on top of the Billboard Hot 100 by co-writing Flo Rida and Kesha's "Right Round." One year later, he collaborated with rapper B.o.B on "Nothin' on You" and co-wrote Travie McCoy's "Billion...