^There's a good deal of Trek fiction that isn't about familiar characters and settings, that adds new characters and worlds and storylines to the universe and that might suit your interests better. The seminal example is The Final Reflection by John M. Ford, which is supposedly a work of historical fiction written within the Trek universe about events occurring several decades before the original series, as told from a Klingon perspective. It's not consistent with modern screen continuity, but it's a terrific piece of worldbuilding and stands as a solid original SF novel in its own right.
More recently, we've had a bunch of series about non-screen characters, including New Frontier, Titan, SCE/Corps of Engineers, Vanguard, and Department of Temporal Investigations.
And, of course, there are the lines that "take over" the TV shows' storylines after those shows ended their TV runs and took them in completely new directions, with mixes of old and new characters. Things like the Destiny
trilogy and the rise of the Typhon Pact.
And novels that illuminate events alluded to in the canon but never seen -- the start of the Occupation of Bajor in the Terok Nor
trilogy, the secrets of Garak's life in A Stitch in Time
, the life of Rugal Pa'Dar after he was forcibly returned to his biological father on Cardassia in The Never-Ending Sacrifice
, the Klingon-Cardassian "cold war" over the Betreka Nebula Incident in The Art of the Impossible
, the Tomed
Incident in Serpents Among the Ruins