When I want happy music I usually listen to jambands and jazz. I will list some of my favorites and give you a brief description:
Medeski Martin & Wood: GREAT funky, jazzy trio. Often times atmospheric. Stand up bass, amazing keyboards, and drums. Amazing at improv.. some of their shows are completely improv and can be downloaded via archive.org and bt.tree.org
Galactic: another great funky/jazzy band. has a good horns section. and also has the amazing Stanton Moore who is on Corrosion of Conformity's new album.
String Cheese Incident: Feel good jamgrass/jamband. good summer music. excellent mandolinist/violinist named michael kang. great drums, great acoustic guitar. good keyboards, but the guy is a pretty big dork.
Umphrey's McGee: Best new jamband in the scene right now. I can't stress these guys enough. They are as musically gifted as most metal bands, and they also give metal props every now and then by covering metallica (they play ...And Justice For All quite well) and pantera. they even did a dimebag tribute shortly after his death at some of their shows. Very fun jamband that have amazingly diverse songs, and they play some of the most hilarious covers at their shows(eg. Van Halen - Panama, Dont know - Sister Christian). Never know what you'll get with these guys. Check em out.
Robert Randolph and the Family Band: One of the best slide guitarists ever. Period. Can't help but dance to this stuff. Makes me feel like I'm in a black church stomping my feet or something. Very energetic.
Yonder Mountain String Band: Entertaining bluegrass. Very fast paced at times.
Michael Franti and Spearhead: Reggae/Rock/Political stuff. Very fun. Very good songs. Some are folk-like.. others reggae, others rock.
John Scofield: my personal favorite jazz guitarist.. he's out there.
those are just a few. i got a million others. just message me if you want any more.
a few others: Soulive, moe., gov't mule, widespread panic, hot butter rum string band, phish, addison groove project, leftover salmon, green lemon, disco biscuits, the big wu, sound tribe sector 9, and check out
you can download almost any of those bands' shows from archive.org and bt.etree.org
many of them soundboard recordings too.. i hope at least someone checks out one of those bands or else that was the biggest waste of time in my life.. just message me if you want anymore suggestions..