1) look at the patterns at knitty.com - many of them are plus-sized
2) look at "men's" patterns - they are larger sizes, and many are more uni-sex than manly
3) get this book:The Knitter's Handy Book of Sweater Patterns: Basic Designs in Multiple Sizes & Gaugeshttp://www.amazon.com/Knitters-Handy-Book-Sweater-Patterns/dp/1931499438
"Created for knitters who want standard sweater patterns in a variety of sizes and gauges, as well as those who want a template from which to develop their own designs, this book provides easy-to-follow charted instructions for 18 sweaters, three in each of the six most popular sweaters constructions. Each style is then provided in 15 sizes ranging from toddler to large adult, then further divided into six possible gauges: 3, 4, 5, 6, 7, and 8 stitches per inch combining for 90 options for each of the six styles, or 540 patterns in all. The cardigan and neckline variations make for more than 1,000 patterns."