For the sake of making a list and checking it twice...
The Lost Era books are:
(the original 2003-2004 mini-series)
The Sundered (Captain Sulu on the Excelsior)
Serpents Among the Ruins (Captain Harriman and the Tomed Incident)
The Art of the Impossible (The Betreka Nebula Incident -- Klingons vs. Cardassians)
Well of Souls (Captain Garrett and the Enterprise-C)
Deny Thy Father (Early Riker)
Catalyst of Sorrows (early Sisko)
Later additions to the series are:
The Buried Age (Picard between the Stargazer and Enterprise-D)
and the Terok Nor series
Day of the Vipers (occupation of Bajor)
Night of the Wolves (rise of the Bajoran resistance)
Dawn of the Eagles (the final years of the occupation and the Cardassian withdrawl)
(as an aside, though the Terok Nor books are obviously related, they can each be read independently. The main characters shift from book to book, and you don't need to have read a prior book to understand what's happening in a later one.)
Other novels in the "death of Kirk to start of TNG" timeframe include:
The Captain's Daughter (Sulu and Harriman, a year after Kirk))
Vulcan's Forge (Spock and Uhura (mostly Spock), a few years after Kirk)
Vulcan's Heart (Spock, Saavik, Romulans, and "Yesterday's Enterprise")
and the entire Stargazer series:
The Valiant
Gauntlet
Progenitor
Three
Oblivion
Enigma
Maker
In addition, there are short stories in this period in Tales from the Captain's Table and Enterprise Logs anthologies, plus a number of TNG-era books with flashbacks to that period, and a few TOS books with "flash forwards".
Anything I missed?