Star Trek: Online, check it out. Granted its an MMO with standard MMO type missions but the space portions are rather fun and good.
Ground combat is a horrible mess and looks like ass.
So far Im playing it like a story single player at about a mission a day, so it doesnt feel like too much of a grind. It works since these story arc missions basically take about half an hour to 45 minutes to complete and usually give you a level up at completion.