Do you include social media as a tactic for brand engagement? I think you do but in different ways. Creating a Facebook fan page or group (even a secret one) probably wouldn't be your best shot. This tactic is way too public. You could use Facebook, however, to advertise to your target markets.
Twitter, on the surface, seems too public as well. But, if you have an interesting CEO with stellar thought-leadership ideas, or a philanthropic or humorous side, it's a good brand awareness tool.
LinkedIn is another tool where you can join discussions about your services.
A great Youtube video describing your services is always useful.
A blog is another good tactic for sharing ideas and building your online presence.
A members only area on your website can be used for customer service inquiries.
The balance is finding the right way to promote your business while maintaining client trust. Social media isn't really in the discretion game, but used properly can return real benefits.
Any other ideas?