Let us first of all define the difference between tactical and strategic combat.
Tactics are used to engage and defeat an enemy formation on the battlefield through the use of terrain,,protection,,firepower and manouvre.
Your strategy determins where,,when and with what to battle in order to win the war.
Currently,,the only tactical decision to make are the composition of forces (the number of ships and how they are to be equipped).
We cannot effect the order the enemy is attacked in.
There are no fancy flanking manoeuvres.
All battles are to the death.
However,,I must say Im a bit ambivalent in this matter.
Sure,,it would be cool to directly order the ships around...the first times.
When you done that a couple of times,,it loses it's novelty quickly,,and the fun of it fades even faster as GalCiv is a strategy game
A good example of what can go avry if you mix too much tactical combat into a strategy game is Star Wars Rebellion
where every battle not already lost for sure (one Tie-fighter against the better of the Rebel's fleet) had to be supervised so your ten Star Destroyer fleet wouldn't run away since they had no fighter protection against the four Rebel A-wings.
What really took the cake was that in spite of being able to issue movement orders in 3D,,they did not matter for the outcome at all!
More importantly,,when playing,,I'm already busy taking care of all the strategic aspects of the game as well as extensive micromanagment.
I certainly would welcome the oppertunity to tell my ships to get rid of the enemy troop transports before shooting anything else,,or being able to pull out of a fight going badly and save the ships for another day,,but that's about as far as it goes.
The planetary invasion ideas are interesting though.
Prolonged battles would allow both sides to reinforce the ground forces with additional troop transports while the fleet forces try to make/break the blocade on the invaded planet.
That would require more strategic decisions:
* Should you go for the big apple straight away,,risking to get bogged down into a battle of attrition,,or peel away the less important planets first since they are less likely to get the same resuce efforts from the opponent?
* when one of your planets gets invaded,,you have the luxury of being able to weight the benefits of the planet against costs to defend it.
* what will happen in a longer perspective? Does the enemy have reinforcements of his own at a convenient range?
* is it worth to continue the battle even when it has dragged out for a couple of months,,or is it time to pull the plug and cut your losses?
It would certainly make strategic assaults much more difficult to pull off,,with no more one-turn wipeouts of relativly equal sized opponents.
(In my current game,,Altarians surrendered to another hostile race after losing a third of their planets since my 51 speed invaders simply couldnt get there fast enough. That resulted in me reloading the autosave,,wait for all the transports to arrive and then take all their planets in a single turn).