To be honest, in my past seven+ years' experience of buying and selling domain names, I personally have never preferred to use whois privacy protection to any of my domain though it minimizes spam, protects personal information, prevents unsolicited marketing outreach and protects against domain name hijacking. However, in some of the client's case, I've as they're too cautious for avoiding spam and keeping their personal contact information too private. However, this doesn't necessarily mean your website, too needs to be private. It largely depends on the reason behind the information that you want to reveal or disclose. But consider the scenario this way if you are a vendor selling items and your prospects wants to know something about you for the confidentiality purpose only and they do a WHOis and they wonder why you have to hide it. Have you imagined what impression you would have left to the particular prospects?
Also I can relate to the sad part faced by many domain owners of getting sales call all day which is very annoying! Also, don't get wrong, if you get domain privacy protection for free you can use but kindly consider the consequences it might result before making any decision.
Hope it helps!
