If we are talking about essential Frank Sinatra albums for a music collection, the first one would have to be 1954's "In the Wee Small Hours," a superb collection of ballads that helped establish the former bobbysoxer heartthrob as the premier saloon singer of his generation. But the second album on that list would be 1955's "Songs for Swingin' Lovers," in which Sinatra and arranger Nelson Riddle go in the opposite direction, providing a stellar collection of pop standards reinterpreted for the crooner who was becoming a damn fine singer. Several of the songs, such as "Pennies From Heaven" and "I've Got You Under My Skin," actually predated the start of Sinatra's career, but in the case of the latter Sinatra provided what is arguably the definitive version of the Cole Potter classic and the song that in retrospect defined Frank Sinatra as the premier vocalist of the 20th century (sorry for the understatement). The zesty tone for the album is established with the opening track, "You Make Me Feel So Young," while other great tracks if you had to be picky would be "You Brought a New Kind of Love to Me" and "Too Marvelous for Words." All of these songs give you the undeniable sense that Sinatra is just having a great time singing each and every one of them. Riddle's arrangements, done with a core rhythm section and a full orchestra, are the key to unlocking the door to musical greatness and are as fine as anything he ever did for Sinatra or anyone else. Part of the problem is that nobody really remembers what most of these songs sounded like before Riddle and Sinatra reworked them into the songs we know today. I may well change my mind tomorrow, but today I would make the case that "I've Got You Under My Skin" is the greatest Frank Sinatra song.