First off, congratulations! A redesign is a big accomplishment, especially when you make great strides in usability.
Do you have any partner organizations, local agencies, or chapters who can also announce the launch? That will provide additional visibility for you.
We always recommend letting your community know that the site is under redesign. Did your members already know of the project? Did they participate in any surveys or interviews? If so, use your outreach to thank them. If not, at least say "we heard you". I'm sure they knew the site was in need of redesign.
You may want a series of posts and/or emails. Include different features in each to build excitement leading up to the launch. If your blog is also on your website, it makes good searchable content rather than throwing all the new features into one big blob of text.
Let your members know that you want their feedback when the site goes live. When they understand that the website is ever evolving, and that their input is important, you will earn their buy in and loyalty.
Best of luck!
Dori Kelner, MS | Managing Partner
Sleight-of-Hand Studios LLC
firstname.lastname@example.org | 703.758.7178 | http://www.sohstudios.com
Get Relevant. Be relevant. Stay relevant.
strategy - design - web - photography
Hey Kara,I'd recommend sending out an email marketing campaign to your audience. MailChimp offers a 15% discount to nonprofits and charities. It's the same platform we use to announce new website redesigns to clients. We love it because of the drag and drop interface so rolling out new campaigns is pretty easy once you've got content in place.
I hope that helps and looking forward to seeing your new site, as that's our speciality!