I find that advertising in the yellow pages is a big waste. Perhaps it's my particular business. We are not really a mainstream business the everyone can use, like a book store or candy store. Most of the customers that search us out are professional repair shops. Over the years, our best advertising has come from networking and word of mouth. I plan to reduce my yellow space over the next year. Maybe just some basic 1 line listings.
As for newspaper ads: I don't think people actually read the paper to search for ads & listings. Although I do enjoy going through the Sunday sale section in the Sunday paper. Not so much because I'm looking for anything special, but just looking at the sales. Maybe something like: Sears has drills on sale and I could use a drill and I can save some money, so why not. Though I did not set out to look for a drill.
I also use the y pages as a sales tool. I can look through the book for businesses that could benifit from my services, I can then make some cold calls.
I guess I'm "old school" enough to use th y pages when I want to buy something also. It also depends on what I' searching for. If I'm looking for a pizza joint in my neighborhood I'm not going to look on the internet. Actuall looking online is more hassle than picking up a local book and looking.