[Suicide Junkie]

I'm no graphics artist, but the halos seen around stars would make great atmospheres, IMO. Coloured to match the type of atmosphere, of course.

You could always simply add blinking nav beacons to the map around planets, just like you have buoys on lakes to indicate rocks & stuff.

Unexplored or undeveloped systems without such nav beacons would of course be more hazardous.