Main Theme - Wii Sports Resort

2 AM (Snowing) - Animal Crossing New Leaf OST

Songs that can be requested on Saturdays at Club LOL when asking for songs sounding "A little sad".

Tomodachi Collection - Street Corner Live:  Refreshing Bossa Nova-Ish
Composer: Daisuke Shiiba, Asuka Ito, Riyu Tamura
Platform: Nintendo DS

All of K.K. Slider's songs on a convenient page. (Well, at least the New Leaf songs.)