Flag Full of Stars and Traitor Winds are both fairly forgettable IMHO, and they're not actually all that connected to Lost Years, but I wouldn't say they're actually bad, just that there are better choices.
If you like Wounded Sky, for instance, you should definitely read Diane Duane's other TOS novels. (Note that some of them weren't originally (explicitly) set in the movie era, but in the current understanding of continuity that's where they'd fit.) Doctor's Orders and Spock's World are both thoroughly enjoyable, as are her first two "Rihannsu" novels, My Enemy, My Ally and The Romulan Way.
As for other authors, I'd heartily recommend Federation by the Reeves-Stevenses (terrific, even if it's technically not consistent with modern continuity), Best Destiny by Diane Carey, and The Final Reflection by John Ford — although note that all three of those technically only have *framing* sequences set in the movie era, and are otherwise flashback tales to earlier periods of Trek history, so they may not be what you're looking for.
For something that's genuinely focused on the movie era (set right after TMP), and relatively more recent as well (by a current "litverse" author), Christopher Bennett's Ex Machina is well worth reading.
It's interesting now that I think about it how few Trek novels have been set during the TOS movie years, actually... and even fewer that are memorable... and fewer yet written within the last couple of decades. Seems to me like it would be fertile territory for further exploration, with (relatively) fewer continuity constraints, yet authors of TOS novels really seem to prefer the FYM period, for whatever reason(s).
, but it sounded the most interesting to me. 
