Granville Island is a corucopia of foods, and I'd imagine is a chef's paradise with fresh ingredients of just about every variety. Of course, GI isn't exactly close to where I live and getting in and out of there can sometimes be a pain because the place gets crowded whenever the sun comes out.
One of my earliest memories of GI is the bakery located close to the market. There are usually performers right in front of it and on a windy day, you can smell the scent of freshly baked bread from quite far away.
I've had the bread here, and some of the pastries and sweets and because of the high quality (and I'm guessing the sky-high rent on GI), the prices are a bit inflated.
Another shop I like to go to sometimes (when I'm not suffing my face in the the food court, haha!) is this place. They've got some quiche, pasta, sandwiches and stuff that they can re-heat. I think they're vegetarian friendly, so most of their food doesn't interest me a whole lot, but they are smack in the middle of the market's secondary food court, so it's conveniently located.
The real reason I come here is for the sweets. They've got rum balls that are bargain priced. I get cookies from here as well, but I love the rum balls here...and I'm not even a big fan of rum!
There are countless produce, meat, seafood and cheese stands scattered througout the market, and sometimes it's worth going down there just to see all the wonderful foods. If you're an out of town foodie, Granville Island's public market should definitely be on your list of places to visit.