>Oh god, talk about good timing. I just got a literal headache spending the last hour searching for a good cross-platform calendar AND todo app that would work on my Mac, and perhaps on Android (although that's bonus). And ideally I'd like to have integration with Trello, so I can schedule my work tasks into the day.

I've been looking for the same, and now I use OneNote for note taking and to do lists. You can easily make kanban boards, you can link tasks to emails or notes in OneNote with more information, and tasks show up in your calendar or tasks in Outlook.