Sunday Afternoons:  Slack Key Guitar Concerts.  Traditional Hawaiian slack key guitar and `ukulele concerts.  April 1 – Ahupua`a: Mountain to Sea; April 8 – Slack Key Tour of the Islands; April 15 – Sea Turtle Serenade; April 22 – Hawai`i’s Sunset Music; April 29 – Kaua`i’s Slack Key.  Award winning traditional Hawaiian slack key guitar and ukulele concerts featuring songs and stories telling its history.  Tickets $25 general admission, $20 Ages 13-19 & over 50, keiki under 5 free. Free…