Bobby McFerrin's "Don't worry be happy" CD. Seriously, it has some great songs on it!

I don't know this band, but they have samples and have listed their CD as "Happy" music: Bayou Brothers, zydeco.

In a google search, this came up at CDBaby as happy piano music: Clay Cotton. There are some rave reviews there. From the samples, I'd say it's pretty happy sounding blues/boogie piano/singing.