A lot of interesting map potential out there particularly since this is a PC game.
Rings of Saturn (With moving asteroids as obstacles)
Kuiper Belt (With moving asteroids as obstacles)
Jovian atmosphere (With weather effects and pockets of moving explosive gases)
Nebula (With weather effects, electrical discharges, ice and rock obstacles)
Orbital Bone Yard (Where decommissioned ships are the obstacles)
A battle in close proximity to the sun around an orbital energy mine including flares and radiation bursts as dangerous obstacles.
Severely damaged Dyson Sphere which was abandoned by it's alien builders so it is now drifting through space passing our solar system (sky's the limit with the interior, obstacles and dangers) This could be the home for numerous maps including abandoned alien cities, forests, mountains, near the corona, in the open atmosphere near dangerously malfunctioning alien machinery.
Assault the Space Station mode with each team having their own station which will involve a defend vs destroy scenario where each side must balance the need to destroy the enemy stations defenses with the need to defend their own station and repair their own defense network.
Carrier capital ship defend/destroy similar to the above but the carrier has both weapons and NPC fighters.
It would also be nice to see factions with wars and an alien incursion, maybe a rogue black hole creates a wormhole where we must fight to defend our system.
Weather effects can impact ship handling.
Electrical discharges can reduce sensors and accuracy
Ice and rock obstacles can cause kinetic damage
A fan designed ship contest would be a fun way to drive interest in the game. The winner gets a founders pack and/or a pile of in-game currency as well as their ship entering the game with a name of their choosing. Of course there would be rules associated with the names as well as basic ground rules for the ships such as size, weapon placement and etc.