Many small businesses credit SEM for attracting new customers. Depending on the competition in your business, relying on unpaid, organic Web traffic via SEO may leave your business far back in the rankings. By paying for SEM, you have more control over the specific keywords that will promote you, as well as where you will appear on the search results page.
A good example of a basic but highly functional website would probably be Majestecsocal.com. However, the exact type of design you should be considering depends on your target audience and niche. In some niches (like the one the example website is based around), users would want to have everything in one place, and hence a basic but very functional design would hit the spot pretty well.
Not all web traffic is welcomed. Some companies offer advertising schemes that, in return for increased web traffic (visitors), pay for screen space on the site. There is also "fake traffic", which is bot traffic generated by a third party. This type of traffic can damage a website's reputation, its visibility on Google, and overall domain authority.