Startup Idea : SaaS Social Media Analytics

For Startups, Brands and ECommerce: FB, Pinterest etc. provide a nice statistics page (how well do my posts perform, which content is more engaging than others etc.). But how about a service that would take those insights to the next level? Show statistics over all plattforms. Compare your numbers with those of your competitors. Receive suggestions on when to post and what to post. The whole service should improve the marketing which is getting more and more complex as many social plattforms arise and companies need to be present on all of them.