I design each type of mining station in at least 2 configurations, one oriented for defense against a small number of enemy light ships, and the other a "Light" version that is much lighter on weaponry and much cheaper - this is for areas which are either peaceful or so dangerous that the fortified version will fall as easily as the light one. When Long Range scanners are available, I often have a scanner version. I like to long range missiles early on, then a fighter bay when available to give the base some counter to standoff opponents and enemy fighters.
Starport permutations outside the normal schemes include fleet bases ("Large" for attracting fuel but otherwise small without labs but ample docking and repair facilities and strong defenses), "starter" very small bases with the minimum facilties needed to provide services to the planet and shipping and including light armaments and moderate defenses, and variants of the latter including Scanner, Fortified and/or Fortified Fleet versions.
For base defense, patrol craft need to be fast enough to catch what they are chasing. A system defense ship can be designed with minimal thruster engines to allow for a large increase in weapons/defense and can be stationed at a base under construction or that needs added defense, and then moved elsewhere by hyper as the strategic situation changes. It is basically a small movable defensive base - like a defensive base, it is useful only when the enemy has to come to the defended target.
For overall deployment strategy, remember that at hyper speed 15,000 it takes over 4 months to cross one 2,000,000 wide sector, or 100 days at speed 20,000, so positioning your main fleets and regional reaction forces must take into consideration how long a base can hold out. The same logic applies to positioning troop transports and garrisons to deal with revolts or invasions. Long range scanners are soooo important for directing operations effectively.
< Message edited by Keston -- 7/21/2014 9:30:22 PM >