In order to better organize a series, I'd love to see more guides functionality + the ability to add a text field as a simple label.
I'm working on creating a large "push" series and another acquisition series, and they'll be long and complicated.
The guides will help line up and visually organize the blocks, and the text labels will help label large sections of blocks.
Both of these together will help with viewing and creating the series, introducing and explaining to colleagues, and searching and editing an ongoing series.