Summer music is always happy. My playlist for instant happiness:
Lovin' Spoonful - Summer in the City
Mongo Jerry - In the Summertime
Genesis - I Can't Dance
The Who - The Seeker
Bobby McFerrin - Don't Worry be Happy
Van Morrison - Brown Eyed Girl
The Kinks - Sunny Afternoon
Cream - Crossroads
The Velvet Underground - Sweet Jane
I still don't see how Leonard Cohen is the most depressing artist, most of his music is pretty upbeat.