Based on your needs, which is the best tool for you? The right choice is easy. Both Direct mail and EDDM have their specific purposes.
Do you have a mailing list of customers and you want to let them know about a specific sale? Then direct mail is the way to go. You will only spend postage to a select group of people that you know already frequent your shop.
If you're trying to hit a specific region, they will both work. But why would you spend double on the postage of direct mail, when you could do the EDDM for half of the postage price. Since postage is the most expensive cost in a direct mail campaign, definitely save your money. Also, no worries about the cost of the mailing list either, there's no addressing an EDDM piece.
EDDM works like this. You go online to USPS.com and make an account. Once you get your log in, you would then go the EDDM part of the site. From there you put in your city or zip code to get the specific routes in that area. There are other perimeters to consider, whether you want to hit P.O. boxes and rural areas. But it's easy to see in the list how many are residences and how many are businesses. It will allow you to break it up at your preferred ratio or pick heavier on the residential or business side.
The drawback from this fancy program is that you cannot only target businesses or residences. You can get close, but you have to hit the entire route, sometimes leaving business to business companies spending half their budget reaching residences.
Another reason to love EDDM, the mail pieces must be at least 6.25" on one side, so they are nice and oversized. They really stand out in the mail. A great poster for an advertisement. Put an image that will stand out and grab people's attention. It will make a big difference.
Below is the EDDM we just ran. I live in Florida, so the tropical images hit nicely here. Some people save them just for the image.
Below is a link to learn more about the EDDM program through the post office.