On our latest edition of "What's New," singer Kurt Elling offers up a mellow rendition of a swinging Frank Sinatra classic, Diana Krall does a crunchy take on a Bix Beiderbecke-Bing Crosby 1920s standard, Brad Mehldau dips once again into the pop songbook, and saxophonist Houston Person applies his warm, burnished, veteran soul-bop tone to a couple of Great American Songbook chestnuts.