The music in Wii Sports has no official track titles released by Nintendo. The soundtrack consists of short, looping jingles per sport/menu.
Fans commonly refer to them by sport:
Composed by Kazumi Totaka (known for Animal Crossing, Luigi's Mansion, Yoshi's Story). His signature "Totaka's Song" is hidden in the game (wait ~2:30 on the Mii Channel or specific menus).
Want a specific track described? I can help identify it.