Eh? The closest thing to "serialization" they did was Worf's discommendation thing, and even that only lasted a year and a half and was brought up in four episodes. And maybe the Worf and Alexander storyline that was featured throughout season 5. which did eventually lead to a friendship and almost relationship between Worf and Deanna in the later years.
As for recurring guest stars, assuming we're not talking about the annual appearances of Q or Lwaxana Troi, than the only truly recurring guest stars were Guinan and Chief O'Brien. After that you have Alexander, who appeared eight times, Ro Laren who appeared eight times and Admiral Nechayev who appeared four times.