Really useful is "The Knitter's Handy Book of Sweater Patterns." It's great because instead of locking you into one kind of yarn per pattern, it gives variations on all its patterns based on the gauge you get with your yarn. It can be sort of laborious to make your way through the resulting patterns, but you get to feel some freedom to create your own patterns.
To go along with it, one of Barbara Walker's stitch pattern books would be useful.
Also: Anything by Elizabeth Zimmermann is worthwhile, although she isn't so much a giver of patterns as a suggester of methods.