Disclosure: this is a blatant try to get some ideas and feedback to pursue a business idea.
What is your biggest pain point when you do social media marketing for your clients?
And if a solution existed for this problem, would you pay a nominal monthly fee for it?
The big one: Connecting all of the activity, in aggregate, to the bottom line.
Getting organic exposure on Facebook. Major brand pages spent a fortune on building their audience, and now only a tiny fraction of that audience sees their updates unless the brands pay more for sponsored exposure. I'd rather pay for a service that significantly increases my organic exposure and out-compete other brands than have to out-bid them.
Finding opportunities for breakout growth on new platforms, figuring out when they're at a critical mass to make the effort worth it, but not over-saturated with competition. Every social platform has had a golden age for marketers on it when good content and creative effort was all you needed to really spread on the platform and get a lot of attention for participating. I and others want to find new platforms when there's an opportunity to win on them.