As the title suggests, the single biggest QoL improvement for me would be to add the planet population window, including growth, to the shipyard.

I spend a lot of time clicking the "shipyard empty" icons, then closing that shipyard to click on the planet to see if there's any excess population and, if so, if its someone I'd rather put in a constructor than a colony ship, then back to the shipyard to produce whatever ships I need only for the process to start all over again when the queue is empty. Multiply this by every core world and it adds up to a lot of time. 

If the population info was instead available in the shipyard it would solve all of it so can we please, please, please get that? Please!