Okay, this one was hard 'cause most of the songs that make me happy fall into other categories of the challenge, but Ive finally got one... Or maybe two... Summertime In The City (Scouting For Girls) and Mr Blue Sky (Electic Light Orchestra) 'cause they're both so summery and HAPPY!!
Summertime In The City: http://www.youtube.com/watch?v=haGtWXElfhw
Mr Blue Sky: http://www.youtube.com/watch?v=qLfylx7cMdE