So, just as Eph 1.3-14 is hymnic in nature, I've tried to find some hymns that express humble gratitude for God's election of His people. Needless to say, this is a tough task. Aside from the classic "Tis Not That I Did Choose Thee" [you can listen to my wife and me sing a version we wrote here or read the lyrics here], I could only find a couple others. I think I like the following because I don't know who wrote it, I only found one verse of it, and I can mysteriously hear myraids of people belting out the "Hallelujah!" part. It is called "Sons We Are Through God's Election."
Pause, my soul, adore and wonder
Ask, "O, why such love for me?"
Grace hath put me in the number
Of the Savior's family
Thanks, eternal thanks, to Thee!