-There needs to be a button on the planetary inventory screen & planet surface screen that either centers the space camera on that planet OR a minimap, otherwise its like planet X somewhere amongst mabye 50 planets has finished building what do you want to build, WELL THAT DEPENDS ON WHERE IT IS more often than not.
I agree with you, that "center planet" feature would be nice to have as an option. But consider naming your planets with meaningful names like for instance, this is how generally how I name planets:
<Name> <Class> [Special Feature] [Geographical Hint]
Examples:
1) "Orion 24 Lab South Border" (Research focused planet very high quality near the south border)
2) "Antares 6 Neutral Zone" (because it is inside a very disputed well known area of the galaxy)
3) "Caprica 16 Mine Inner" (inside inner region of your territory, unreachable to your enemies and focused on production)
4) "Kyro 7 Outpost Drengin" (for a more precise location and function, near Drengin, with Invasion defense due to its vulnerability)
I know this "naming" could be a bit overwhelming in Huge/Immense Galaxies but it has been working for me.
But again, the center planet action option would be very nice to have in next patch/version/whatever.