I was looking through the FAQ and one thing I noticed missing through all of that is a mention of which novels are set in the TOS movie era between The Motion Picture and The Undiscovered Country. As Star Trek II, III, IV, and V are almost back-to-back except for a few months on Vulcan between III and IV and however long it took Enterprise-A to limp back to Spacedock after Kirk wanted to 'see what she's got' at the end of IV, the two areas are really between The Motion Picture and The Wrath of Khan and between The Final Frontier and The Undiscovered Country. Unless you count any time between the end of the WhaleSong Incident and when the crew is assigned to the Enterprise-A. I know Spock's World is one because it talks about Kirk being voluntarily demoted from Admiral. Probe would be another for obvious reasons. Star Trek New Earth is another as they talk about the new maroon uniforms in the first couple of pages. Is there a timeline for novels I could look this up on? Are there any novels you would place in that time frame even if the picture on the cover is with characters and ships from the TV show? Also, does anyone have a Top Ten list of their favorite TOS movie era novels?
There's an old site, no longer updated, that should give you the info you're looking for. It's probably only missing one or two stories published since it was last updated: https://sites.google.com/site/stvotitimeline/
I use memory beta's timeline (just ignore the non-novel things). I've included the link for 2273 (when the Motion Picture was set). http://memory-beta.wikia.com/wiki/2273 I've not read them yet but on my to read list I've got the following books set inbetween the Motion Picture and Undiscovered Country. Someone else will have to comment if they're any good though. ST:1 Ex Machina DTI: Forgotton History Firestorm Ice Trap Death Count Shell Game The Wounded Sky Doctor's Orders Spock's World Rihansu books Rules of Engagement Deep Domain New Earth books The Pandora Principle Dwellers in the Crucible Strangers from the SKy Time for Yesterday ST2-4 Unspoken Truth To Reign in Hell ST5 In the Name of Honor Probe Excelsior: Forged in Fire (which I have read - really good Sulu story linking to DS9's Blood Oath) ST6
You might want to also check out the timeline in the back of "Voyages of Imagination". It only books released upto December 2006, but it is the most recent official timeline.
The site I linked above is by one of the Voyages of the Imagination authors and is a bit more updated than the one in the book.