Back in March, Smart Mapping was added to ArcGIS Online. One of the aims is to make it easier to produce effective maps of your data, but it also adds sophisticated style options to ArcGIS Online. If you haven’t looked at it yet, or have only used a few bits, it’s worth taking a look through the series of blog posts on it:
The accompanying map images might give you some new ideas about presenting your data to get the best out of it. One of the functions that piqued my interest is the ability to apply transparency based on an attribute to emphasise data with high (or low) values. I also really like the handle slider controls for the data classifications. They are easy and intuitive to use - with immediate feedback - but still show the underlying data distribution. You can either choose your settings by trial and error or by making use of the distribution.