Need suggestions for Marketing SaaS. What am I missing?

I’m not looking to reinvent the wheel. I’ve had success selling Marketing SaaS solutions at a few different companies, in a number of industries. I’m done having other people get rich off my hard work.

Here’s my question: What platform would you recommend, if I want to create my own SaaS Marketing solution?

I will drum up the business. I can create the content. All I need to do is create email newsletters that go out to the client’s email database every two weeks, and need to automate posts to the social media three times a week. That’s it.

The MVP can be cobbled together. Ideally, we’d continue to iterate on a single SaaS solution where the client could log into their dashboard to see upcoming outgoing content, make additions to outgoing newsletters going out every two weeks, and even post to their social media pages directly from the dashboard our SaaS provides. But, I don’t know if their exists a software solution that can do this out of the box.

I’ve been looking into bubble, softr, and air table. I’ve been considering othe frankenstein solutions. For example, using mailchimp for client’s newsletters and some other platform to see all of the client’s social media from one place… (zapier + ???).

Any thoughts, wisdom, considerations are greatly appreciated.