The Buried Age by Christopher L. Bennett (July 2007), involves what happened to Jean-Luc Picard between the loss of the USS Stargazer and his assuming command of the USS Enterprise-D.
One Constant Star by David R. George III (June 2014) involves John Harriman and Demora Sulu encountering an unusual planet and the Tzenkethi.
Another Lost Era novel would have involved Benjamin Sisko serving on the USS Okinawa during the Tzenkethi War. However this story never progressed beyond the proposal stage and was subsequently abandoned. This storyline was later included in the Star Trek: Typhon Pact novel "Rough Beasts of Empire" by David R. George III.