Peace-time?  This is an alien concept to the Kzinti!   They should be placed somewhere convenient for the next war you will launch...

Sentient species taste better...

In time of war and peace (no pun) I place fleets on a perimerer around the part of the galaxy I have/attacking.  It's basic military tactics.  If you've played war games, follow your instinct.  I don't use military starbases (for attack or defense) if thats what you meant.  If you mean protecting military resource starbases, by all means.

@KP...witty.

Hmmm. Strong perimeters are subject to penetration/exploitation (although I'm not sure the computer opponents are that smart--they seem kind of slow). I suggest a few very strong fleets at (interior) strategic locations, and use of interior lines. It's (barely) working for me in my first game--so far. I keep a small force (e.g., two heavy fighters) at strategic points on the perimeter to discourage cherry picking unguarded planets (usually all of them, except for ships in repair, fleets abuilding, reserves, etc.). Leaving ships in orbit is a waste of maintenance fees--they should be out hunting hostiles, picking off mines, patrolling, generally keeping the aborigines off balance.

Well, it's all relative.  If the enemy is coming at you with small hulls and a couple weapons points, you can beat them with small hulls and a few more weapons points.  The AI fights with small hulls for a while.  They don't come at you right away with the heavy stuff.

It's true that you get a weapons bonus for planets in orbit, but unless you're playing with a very small number of habitable planets, it's generally not efficient to build ships just to park them in orbit.  You have to build so many, you have no resources left for offense.  The game ends up in a stale mate or slow grind at best.  Of course, the game can be played any way you like and if a long drawn out game is what you enjoy, then go for it.  I like my games short and they usually don't last more than a few years.

I was going to mention a perimeter defense would be useless against another human player because perimeters can be overrun, but in this game we play against the computer and perimeters work in that case.  Although, I have been overrun by the computer before, but it's pretty rare.

Keep in mind how the "Neutral Space" UP Treaty can affect you.  That is, any ships in what becomes enemy space will get teleported to a boundary.  The only exception appears to be ships in orbit around a planet, even if that planet is "behind enemy lines". 

This, in turn, means that defenders set to "Guard" at mining starbases will also be thrown out of enemy space.  (And even bases with lots of modules lose most battles.)  In one game, I had three mining starbases close together far from any planets but in another empire's space.  I knew I would lose them at the outbreak of hostilities, so I built and upgraded an Influence starbase in the middle to create a small pocket of friendly space to park the defenders.

In another case, I had just two starbases close together but they were both red bases that I wanted greatly to protect.  They were too close to future-enemy planets to have any hope that i could build an Influence base to include them.  What I did may have been a bit cheesy, but I built a base at the border and added enough mil starbases with speed boosters to let me get my defenders on station instantly upon war declaration.  Just in case the AI bagged the bases in a surprise Pearl Harbor (The Drengi have done that once or twice to me), I had some constructors there, also.

The starbase speed-boost cluster around the major fleet rendezvous is a known device, of course.  It is strongest in smaller galaxies, obviously, where one might be able to completely conquer any enemy on the opening war turn, but it can be useful even in the largest galaxies.

Yea, military rating makes all the difference.  If you get it high enough, you can pretty much control the game.  Building the spin control center and putting some ships loaded with weapons in orbit around it is key.  I rely on that project heavily.

Definitely, I often try to set it up so I can take out an enemy in one turn, Just load up a bunch of transports and fighters to hit 'em all at once.  The game developers tried to counter this tactic by slowing ships speeds from DL to DA-TA, but it's still pretty do-able with the right setup.