I first off have to give a shout out to Boston Interactive for their website design. Probably the most amazing business anniversary site I have seen thus far. Check it out http://www.bostoninteractive.com/10/
This is how we structured our PR:
Celebrating 20 years in business
This year marks an important milestone for our company as we celebrate our 20th anniversary. This 20 year milestone gives us a chance to reflect on our past achievements and highlights as we envision the road ahead for us.
Honoring the past: ... How things used to be, product time line.
Present: ... awards and achievements
Future: ... (quote from owner), where the company is heading
About the company:
We were also able to get some customer quotes before our press release was posted on our website.
Along with the 20 year celebration we posted pictures of the staff members from 20 years ago. Some very interesting pictures of our staff, some as babies and some with hair. We also integrated a customer appreciation day into our celebration as a way of thanking our repeat customers for 20 years of business.