Social media is very useful for B2B SaaS companies. The level of targeting on places such as Twitter and Facebook are very useful to hit the right people/companies. LinkedIn is also another useful tool for B2B Advertising.

On Twitter/Facebook, you can potentially target users of your SAAS, or create look-a-like audiences of your existing users by uploading custom audience lists.

You can potentially target business handles on Twitter, targeting people that are part of say a marketing group facebook page.

There are a number of targeting possibilities to hit the right audience.

Remember that the users of your product use Facebook, Twitter, and LinkedIn specifically.

To be honest leveraging Facebook and Twitter is probably as useful and sometimes more valuable LinkedIn Ads.

You can also work to build a social community within Facebook and Twitter, potentially, to engage with your current users, and potentially run promotions, engagement campaigns, etc.