Don't really know how much you have looked in to the blue book. Like others have mentioned I am inundated with bid invitations from contractors there on jobs of all sizes.
Have you found those to be good leads? It has always been my impression that a bulk of those leads are price shoppers. You do the time to get a good price and they thanklessly use it to beat down the guy who they were planning on using all along.
Quite honestly, I'd love to hear some success stories about landing jobs from cold leads like those. All of my good work has always come from a reference. I've gotten some good service call work out of a listing in the yellow pages.... That's not an ad, just the one-line listing I get with my premium commercial phone line, which was my only option because I am renting a small office from my uncle in a commercially zoned building. That's an occasional call here and there; trust me the phone isn't ringing off the hook. All other work is referral. But that takes time in business to work up to.
I've put together plenty of bids from Blue Book leads, and I became convinced the lack of a relationship with the contractors meant my likelihood of getting the job was extremely low. I never got one. If I had gotten it, I probably would have been lower than I really wanted to be.
I guess it could be similar to fidelity in a marriage. You want a GC that can appreciate what you bring to the table (provided you do). You want someone who trusts your competence, your ethic and your price and realizes the value of having a good sub relationship. I like to avoid the GC who will cheat for the next good-looking price that walks by.