Dim All The Lights

I really love this song despite being a disco hit played at every wedding ever. The build up is really energetic and I think Donna's under water voice is really cool coming in during the instrumental breakdown. Heeyyyybaby!
 -Trov

Bubblegum

I was enjoying Mr. Loco's song Bubble Gum whilst brushing my teeth and realized there is a sweet key change at 2:31.  

It's The Little Things You Do

Delicious and replenishing key change.
-Davey Kiss

Mr Blue Sky

I feel like I'm cheating by submitting this song but the promo video is pretty incredible. Key of F switches to the relative minor for the outro.
-Trov

I Believe I Can Fly

I feel like every 90s R&B song has a key change. Here's one with a half step change.
-Al Bruno