I started to design the planet mechanics I have had in mind in a bit more detail. Mainly working with population growth and food mechanics and how to control the population on planets. People have to eat food to stay alive, but they will require more food to reproduce. Also, the growth rate is affected by the remaining free space on the planet. I feel this is quite realistic and simple. So the growth rate of the population on a planet is affected by the surplus of food and the size of the planet. As players can affect the growth rate by allocating work for farming, I find it convenient that the population’s work allocations can be set to meet desired goals. The goals are: sustain population size, max population growth and max food output (surplus can later be stored or sent to other planets). The allocation of workers then changes automatically once the requirements to meet these goals change. In addition, there is also a weight parameter assigned with the farming plan, which interpolates between these goals. With these tools the player can easily set the desired goals for the planets, hopefully reducing the amount of needed micromanagement.
After some (or all) of the workers have been allocated for farming (thematically all kinds of agricultural tasks, not just farming, whatever is required to get food on that planet) the rest of the workers are allocated to industry and research. There is another slider to set the ratio for this allocation.
All planets have base multipliers for food, industry and research output as well as a starting size. Now they are just randomized, but in the future there will be some kind of correlation between these numbers. Probably by having different types of planets and then using that base type as a starting point for some randomization.