It is interesting what the Open/Libre office package can do in this area. I have recently been tweaking a version of the componentgrades export plugin (it's about exporting assignments configured with advanced grading plugins to Excel).
https://moodle.org/plugins/report_componentgrades
I was working to allow it to export from my BTEC grading plugin. It uses the PHPExcel library and it is possible to do plenty of the nice formatting things that people like in Spreadsheets and the formula lovelyness. It export fine to both Open/Libre office and the other day I discovered it does the same for Excel.