My introduction to fantasy literature was Weis & Hickman via the Dragonlance Chronicles (and Legends) omnibus editions, so I'd be remiss to not mention them. But their Rose of the Prophet and Darksword series have had more of an impact on my DMing.
Glen Cook's underrated Garrett books are a huge influence, as are other latter-day weird fiction writers like China Mieville.
I've been known to steal plots/subplots from Melanie Rawn's Dragon Prince and Dragon Star series. And the early Seven Altars of Dûsarra series by Lawrence Watt-Evans still rears it's outsized, giant-cat-riding head from time to time. Ditto Piers Anthony's Incarnations of Immortality and Bio of a Space Tyrant series.
And all of my campaigns seem to be heavily influenced by Earthdawn First Edition from FASA, and of late I've been more explicitly following a Lovecraftian/Howard/Lieber path.