Science Fiction General

I've been revisiting Rebecca Ore's Alien series (published in the Ben Bova Presents series--Becoming Alien, Being Alien, and Human to Human), and it's made me think of Mary Gentle's Golden Witchbreed and other pre-2000 sci-fi.

Do you guys have any recs from that era? Not the big names, but the authors who put out a book or a trilogy or whatever that's just sort of stuck with you?

I am looking for others’ recommendations for the best Spec Fic stories centered around covert organizations and their dealings/activities. Intelligence agencies, special units, black operations, etc.

Some examples that spring to mind are Special Circumstances from The Culture series and Section 8 from Star Trek.