I think all of the interesting side cast Seeley implemented were in Grayson (Spyral, Skull Girls, Helena, Midnighter, Tiger). His actual Nightwing side cast was pretty bland in my opinion (Shawn, The Run Offs).
Coming from someone who never understood the character`s hype, I actually like Barbara in the book. I think she provides a good counterpoint to Dick. I would love to see DC bring back someone like Grant Wilson as a antagonist/side character for Dick.