I'll second Walking on Sunshine, by Katrina and the Waves...it's upbeat, and since we're currently going retro with the 80s these days, it's perfect being an 80s song. Makes you want to sing, move, smile...at least when I hear it.
Second one that popped into my mind is Queen's You're My Best Friend. Was a really "up" song form me when I was in high school, and there's not too many people that don't like Queen.