Cameras are such a big deal for making something feel like more than a programmer prototype, and especially important to a final game. I hacked together something I was happy with in February for this:
(okay so it turns out nothing in the game really shows what the camera does -.-)
It had a bounds box, position easing and stuff that was good super hastily put together so I kinda just put off making it a thing. It was for Later.
Later is Now!
Not finished yet but everything about this, I'm lots happier with and it does so much more:
It eases position, rotation, and scale to target values with separate execution durations and configurable easing functions.
Plus, some kinda screen shake:
It's not finished yet because the existing camera API was horrible but the behaviour is there looks like everything I think is core game camera stuff :)