The blog Post rings a tune with me. I've started organizing all the work related projects into Trello boards,and have iterated quite a bit on my workflow.
Next to a board for scrum, I also have a board reserved for planning work things to do in the long term future, like a backlog, but coverings many different aspects of company mostly related to software dev, but also some hardware and marketing.
Eventually I wanted to be able to measure how long would it take to complete some tasks, and prioritize them across lists.
The way I solved this way with a plugin for sublime text, the editor I use all day long [0]. The plugin reads metadata I add to each task on Trello like (backend 1d design 4h) and uses it to compute a schedule for all my tasks. It is also able to prioritize between posts, which in in my case are fucus areas.
When I need to prepare the next sprint, all I have to to is use the plugin to tell me which tasks have the highest priorities, and occasionally review the Planning board.
The plugin was initially developed for Trello, but I found it really useful also for offline task scheduling between different projects.
You can read more about how I use it on my blog [1].
[0]https://github.com/pedrokost/STProjectPlanner
[1]http://blog.pedro.si/2015/11/project-planning-in-file.html?m...