In our experience, anyway, YP's didn't generate any more price shoppers than any of our other advertising. It doesn't have to. Price shoppers are price-driven and most YP ads don't advertise price.
If you look in most any directory you'll find a few very nice, professional ads, and a lot of not-so-nice ads, and a few in between. Doesn't it make sense that the more professional an ad looks in relation the competition, the more expensive that company is also going to look in relation to your competition? It makes sense a price-shopper without a coupon will end up in the phone book. Just MHO, but I'd bet an ad that makes a company look "not cheap" ought to discourage many of the price-shoppers from calling.
I wouldn't focus on size as much as I would placement. Most directories place advertisers by size from oldest to newest. Look at the current directory and take your best guess where you'll be based on the size of the ad. We like to be as close to the front as we can afford, but we don't necessarily have to be first. If there's only one half page ad I'd rather be the second half page ad than last full-page ad. You end up in the same general area for half the price. If there are only a handful of full and half-page ads I'd want to know where a quarter page ad is gonna put me and so on.
Look at the mix of color and black and white ads. If everyone is color, will black and white make you stand out more? It's not always what you'd expect.
It's a guessing game. Your rep might be able to help but I doubt it. Most of the sales reps we've worked with said whatever they thought we wanted to hear. Gena spent hours agonizing over size, placement and all of that but her hard work paid off.
Here's an interesting observation. Look at these pics. How much effort and imagination went into this carpet cleaner's ad,
compared to this ad encouraging people to use the YP's,
Or, this cleaner's ad,
compared to this "use us" YP one,
Or, this,
to this one,
or these,
or these,
Sad, ain't it? Why do they put so much effort into their own sales ads and only the minimum into their advertisers?
Do yourself a favor and hire someone to create your ad. I'm sure there are plenty of talented artists close by, and you might even be lucky enough to find someone with experience placing ads.
Personally, I like emotional hooks directed at women. Pics of kids, babies, families, smiles, warm fuzzy stuff and humor. Tout your benefits, a strong guarantee, find ways to put perspective clients at ease. A pic of you, and your staff if you've got any, is a good thing, too. Again, I'd hire a professional. They know how to pose you and the lighting is always correct. Even those places at the mall can do a good job for not a whole lot of money. Make sure they'll give you the pics on CD.
A lot of folks don't like YP advertising. I didn't either for a long time. I told the wife it wasn't any good when she insisted we give it a whirl. We got into several directories. Some worked well, some bombed, Overall, though, once we got our heads around it YP's turned out to be some of the best advertising money we spent.