Reddit reviews Hidden Empire (The Saga of Seven Suns (1))

• Ringworld by Larry Niven
  
  
• The Foundation by Isaac Asimov (Followed by Foundation and Empire, then Second Foundation. Note, there are other foundation novels that both precede and follow this period of the story.)
  
  
• The Dark Tower by Stephen King (7 book series)
  
  
• The Saga of Seven Suns by Kevin J. Anderson (7 books)
  
  
• The Book of Ler by M. A. (Mark Anthony) Foster (3 books in 1)
  
  
• Ender's Game by Orson Scott Card (I haven't read the whole series, it's long; note also that these were written by a trained playwright, so hearing these on audio is most like seeing this on a stage. The audiobooks are available, try a library.)

Saga of Seven Suns might be right up your alley. Three races, space travel and mystery to a level involved.

Hope you like it.