Focusing on Joy:
* Laughter's embrace
* Smile's warm sun
* Heart's bright song
Focusing on Contentment:
* Peace's soft blanket
* Spirit's gentle breeze
* Soul's quiet harbor
Focusing on Excitement:
* Adventure's bright spark
* Hope's leaping flame
* Life's joyful dance
More abstract options:
* The feeling of wings
* The sweetness of dawn
* The warmth of belonging
Ultimately, the best kenning for "happy" depends on the specific context and the tone you want to convey.