Pratchett and Gaiman, Good Omens, Gaiman Stardust, Neverwhere, Aaronovitch Rivers of London/Midnight Riot. Le Guin's Earthsea, except that the gender politics are pretty awful in the three written in the 60s/70s and then she tries to fix the gender politics in the last two and the world-building goes skew-whiff.

I don't know what her pro stuff is like but judging on her fanfic Sarah Rees Brennan's The Demon's Lexicon should be pretty good.