Being 5'9 myself I ride a 19" hardtail and 54cm touring bike (LHT are sized larger). I prefer slightly larger frames for road riding. I had a 17" frame and I felt cramped, but everyone is different.

For a MTB 17-19" should be about right. For road bikes 54-56cm would be about the range. Again, these are ranges and everyone has different preferences and body dimensions (long inseam, short arms, long torso, etc.).