First, let me say I think a business like yours is a perfect match for Constant Contact. You can do so much with the features of the tool to both target your audience(s) and provide information that is of great service to the community.
The communications you send out from Constant Contact can (and should) be a reflection of you, your business, and the image you wish to project (or the aura you wish to create). Constant Contact has many different templates and colors that you can work with to fine tune your communications along those lines. You may be doing precisely that already, from a distance it is difficult to know. But I would be pleased to discuss this with you directly, if you wish, and make some recommendations from there.