It all boils down to your preference and strategy. Broadcast towers are more useful when they are spread out. You also may want to have a powerful shipyard on the front lines, where it is likely needed most.

Some planets have bonuses that change the output of some of your buildings. In that case, it's better to get the most out of it.

Gotta disagree there. Trade ports stack indefinitely in a linear fashion. I start by having one trade port per planet, but once I've got all the labs I going to need, I fill the remaining logistics slots at all my planets with trade ports. The return on that investment is impressive.

Also, you really don't need 1 broadcast tower per planet unless you're trying to use culture offensively. Culture can spread across phase lines to neighboring planets easily. I position my broadcast towers to cover all my planets so I can get the allegiance boosted. I can usually do this with a small number of broadcast towers if I position them intelligently.

As the OP, diversification or unity is very situational. Sometimes I'll make a planet a huge frigate factory but, other than that, I find it's better to have most things spread out, *especially* your labs. That way if your opponent nukes one of your worlds and destroys all the structures, you only lose a few labs, instead of a whole wad of them.

This is only partially true. If you can increase the length of your overall trade route (the white line running through grav wells when you put your cursor over the credit summary) then the income of every single Trade Port you have will increase, making you far more money overall. If you have one trade port per planet already as you say you do, then your statement is correct, but Trade Ports are only linear once you have your longest chain established.

yeah I was amazed.. I never bothered stacking my trade ports. Then after reading this, I tried it out and it was a night and day difference. I made enough cash that I could buy my minerals without much sweat and produced loads faster because of it but this was on Systems of War so it lends to a fair number of planets and distance I guess so perhaps in smaller 1 v 1 systems it might not stack up as well cause of distance (or lack there of).

sooo... stacking at opposite ends of empire is best?!? one at far outpost?