I know this is expanding the scope and complexity and probably opposite to what you're trying to do, but one thing that would be cool is to have different tabs. In my current workflow, I have a notepad for "working memory" which Heynote will easily replace. I also have a separate one to track the things I worked on each day. I need to have a record of who I charged for what incase I get audited. I could totally see having a block for each day - and I wouldn't want that intermingled with the other data.
Oh I would love it if you could render markdown as formatted html a la Typora