I have a 60 song setlist for happy songs (my playlists are entirely by mood, happy, sad, angry, sleepy, chill, etc) according to itunes most played, the top 3 are:
<youtube=nC9P8-B42cA>
<youtube=iPUmE-tne5U>
<youtube=v7MWiYPsh14>
Enjoy and stay happy! =]