Why not eschew sliders altogether and do it the way it's done in the real world -- with the stick and the carrot. Laws, tax breaks, trade incentives, handouts, etc. Want more food production? Lower taxes on agriculture, etc. And then Rome 2 or SimCity-style edicts (as stanirya mentioned) to add more flavour.

Guilds could be a fun way to theme up a slider system. The Farmers Guild tries to obtain subsidies, research grants, etc. for agriculture.

It really depends on the mechanics and their depth, If the goal is to make the game about macro decisions then here are some suggestions:

- Each planet has its own sliders/qualities, this are unchangeabe by the emperor.

For example a desert planet will have low agriculture, therefore the people there won't be building stuff that just doesn't pay off.

- Budget Sliders, or in this case, Infrastructure Construction Budget.

For example the emperor allocates a lot of money to finance the construction of agriculture, therefore the planets will start using this money to build farms, and maybe that desert planet will make a moisture/whatever top notch farm.

- Planet Governors, they have their own specialties and preferences which will influence what is built in the planet. (Appointed by the Emperor or elected by the planet's people, up to you).

For example the Governor of that desert planet has the trait, "Self-suficient" which is a trait that makes him want the planet to be self-suficient, therefore he will be prone to build those topnotch desert farms because the planet doesn't produce enough food to feed itself.

- Budget Sliders, or in this case, Infrastructure Construction Budget.

For example the emperor allocates a lot of money to finance the construction of agriculture, therefore the planets will start using this money to build farms, and maybe that desert planet will make a moisture/whatever top notch farm.

he will be prone to build those topnotch desert farms because the planet doesn't produce enough food to feed itself.

Or maybe laws/edicts/settings based on planet type? Like "encourage agriculture on swamp planets [YES/NO]"?

I don't understand why you won't just let the player set which group a planet belongs to;

it would only need "micromanagement" when setting the group(generally when the colony has just been established)

If you don't want some kind of connection to the map(border-colonies in the military group) i recommend to see the planets as "economic potential"

for example:
edict: research agriculture

total progression-cost : 5.000 RP

turn cost: 100 RP

bonus: +5% for every swamp-colony

So with 10 swamp colonies the player would pay 100 RP / turn and receive 150 RP towards the competion of this edict

Other edict: Allow commercial traders more freedom

effects: +5% taxes for rocky planets, -10% tax-income for low-developed colonies, +5% tax-income for high-developed colonies.

I don't understand why you won't just let the player set which group a planet belongs to;

it would only need "micromanagement" when setting the group(generally when the colony has just been established)

I could go for it, if it wasn't the player setting these groups. For example if planets over time get auto promoted from low developed to high developed or belong to a group based on the proximity to the homeworld (central core worlds and frontier worlds) or based on population or time of acquisition (high pop world/new settlements).