Inactive Prospects (or Contacts)

I have been using a combination of Salesforce ActivityMetric feature and Pardot´s dynamic lists and  

Pardot Last Activity field to keep track of inactive contacts (in my ORG we are only using person accounts, not leads).

I would like to ask for your suggestions and ideas about which (out of the box) automation features or which fields are YOU using (from Salesforce), to find out which contacts are inactive: not opening emails, have recent tasks and so on.

I know the Salesforce field called LastActivityDate, but this does not keep track of email interactions (we have Gmail integration) or related tasks.

Any suggestions?

@* MC Account Engagement (fka Pardot) *