This sounds very interesting.  Already I have a few ideas for where'd I'd want to go with my personal part of the roleplay: 

1. I'd be interested in creating a species of religious Zealots, and focusing my roleplay on their church organization. They'd probably be conservative, racist towards humans, corrupt, and fanatical.  
2. A massively successful and influential, human-origin corporation. Preferably one that produces something absolutely essential to the interstellar economy (think modern day oil). I'd be focusing on all the corruption and politics within the organization, and whatever else may be happening in the story. 
3. A species relatively new to the interstellar hegemony (50 years or so). I'd be focused particularly on their government and high-ranking civilians, and how they have been dealing with integration into the interstellar hegemonic system, and how they would interact with whatever events take place as the story starts. 
4. A colonizing expedition on a new planet. They'd be human or mixed-race, and sponsored by some large and influential company. My roleplay would focus on the hardships of colonizing, dealing with the sponsoring company, and dealing with whatever else is happening in the story. 

These all are just baby ideas of course. They would be scrapped/developed based upon how the lore changes and what other people decided they wanted to do.