i'd be happy to try anything that sounded interesting in either the Post-ENT pre-TOS era or even in the TOS era with other crews, such as but not limited to:
USS Endeavour (seperate from Vanguard)
SCE with the Lovell
Reyes' early career (NO VANGUARD SPOILERS, I'm reading Declassified now)
early years of other VGD characters
something of Sarek's early life maybe.
April's career pre-Enterprise.
i'm sure there's plenty more...