I have been looking for a better option for polygon shadows also. What is working best for me so far is using the Move To tool. It creates a drop shadow the same way that the move tool does, but with Move To you can input specific parameters of how far you want the features to be offset. This is useful for me because my information changes semi-regularly and I need to make the shadow the same every time (I use the Delta method with X=3m and Y=-1m). Here's the result:

If you are using ArcGIS Online, there is a Drop Shadow Effect which looks really nice. I cannot use this because the effect doesn't carry into the web application I use, but depending on your needs it may be a good option. Here's what it looks like:
