I got one the other day that was just too good to be true. I saved the game before I did anything so I can go back and play it from the beginning using different strategies.
These were the bonus tiles on this planet.
Manufacturing
(1) 700%
(1) 300%
(1) 100%
Research
(1) 300%
Food
(2) 100%
1100% manufacturing bonus from 3 tiles, and add to that the Manufacturing Center which gives another 50% to the planet.
300% research, doubled to 600% by the Tech Center for that tile.
Add to that the Economic Center.
This was one kick but planet.
Once I got all the buildings in I could pump out fully loaded medium hulled ships in a 2 weeks flat, large ships in 4, and huge in 7.