a 2d hex or coordinate based battle would be fine as long as it allowed for a diverse range of tactics.
Some questions that may not have been answered yet :
Can players see opponent's approaching fleets in the starlanes?
Do the starlanes always drop ships out at the same location within a star system? (simplifies defending the system if the badguys always arrive in the same location)
The starlanes represent some form of current in the space time doohicky, so fleets sail these currents. spacelanes are a representation of the fastest route between systems using known currents / whatever. A ship can choose its insertion point to the system, as can a fleet...
Ok, i just read the whole thread. There are some intersting ideas. I synthesized some of them into a concept about the field on which battle will be fought, that hopefully encourages tactics/strategy:
First, 2 ideas i considered and rejected:
• If starlanes always exit into a fixed point in a star system, all the battles in a given system will start to look alike. The attacker's element of supprise is limited to the composition of his fleet. This would tend to favor defence too much. Too Predictable. Boring.
• If a starlane can be exited and entered at any point of the system, then battle in a given system is varied, but perhaps too un-predictable. An asteroid belt isn't much of a barrier if you can start out inside it, and no planetary position has any inherent advantage over any other. Also i'ts much harder to lure ships into a trap if they can flee the system at any point, even if a large charge-up before "jump" is required.
• So i propose that ships can only enter/exit the starlanes at the periphery of the system.
Now the supporting technobable for my concept: The starlanes are tunnels, lines, whatever between the gravity wells of stars. However it's harder to enter or exit a starlane close to the bottom of a gravity well. Therefor ships enter/exit a starlane near the periphery of the system. With less mass, small ships can enter/exit a starlane further into the well. This would favor smaller ships for hit-and-run tactics. As starlane-drive technology increases any ship may enter or exit the starlane closer to the central sun.
The system battle map is a circle (or ellipse) centered on the system's sun. All planets are placed in orbit around this sun. Asteroid belts create natural barriers to ships and fire. Ships: slow down or take damage. Fire: has a chance of being blocked. The aggressor(s) when entering a system will not know the deployment of the defender(s)' fleet(s). He chooses the insertion points for his fleet— limited to the periphery of the battle map (as explained in the previous paragraph). The Defender can tell where the attacker will exit the starlanes, and perhaps the combined mass of each group, but not the exact makeup of the attacking fleet(s). He positions his ships to respond.
With this set-up, planets nearer the sun are more easily defendable, since the attacker must travel further (possibly through asteroid belts) to take a planet. The further inward he goes, the harder it will be to escape far enough out of the gravity well to regain the starlanes, if battle turns against him. A player might defend a system by placing many defences on a outlying planet that has little other value, thus fortifying the system.
As a side point i like the idea that battles cannot last indefintely after X number of turns the battle should be suspended until the next turn. 1) this keeps battles from going on indefinitely. 2) the allows the strategic option of stalling until reinforcements can arrive.