I can sympathize with the guy hooked on Weber books. Although he doesn't write truly great sci-fi, his books are terribly addictive. Another addictive writer is David Gemmel. He is not a great fantasy writer but a great storyteller. I've just started reading his "The swords of night and day", a book in the Drenai series.
Sci-fi that I can recommend is Dan Simmons Hyperion series and David Brins Uplift novels. For fantasy you can't beat Guy Gavriel Kays books like "Tigana" and the "Fionavar tapestry" series.