A press release campaign is a vital PR necessity, but there are other useful activities that can be done in conjunction with it:

Support Local Groups and Causes:

You should create good PR relationships and present a good image within the community, creating something newsworthy for the local press or to include in your social media.
Social Media PR:

Use social media PR to your advantage. Create and update all your social media pages. Add timely information and promote your PR wins, and further promote any publicity you receive from your other PR efforts.
Become an Expert Speaker:

Be prepared to speak at local universities and schools, business associations, professional networks, charitable organizations, etc. These speaking engagements often lead to valuable contacts, including the media.
Sponsorships:

In addition to being a supporter, have your company become a sponsor of something special. Remember that what you support should reflect the image you wish to create. For example, if your product is associated with youth and vitality, sponsor a local/state school sports team or 5K run or something similar. If your image is artsy, sponsor a local art exhibition or dance troupe for their next production.