A couple things come immediately to mind, not knowing what granularity you need. Such as is it at the ZIP code level, the street level, and the state level, etc.
Microsoft MapPoint has a specific function for such things that any version that can run on your current OS should be adequate. It uses BING Maps vs. Google Earth. It had its limitations but I still found it useful and being a Microsoft Product was something I could easily get approved for use in our environment. It unfortunately has been discontinued on 12/31/2014, but it is still available from retailers and older versions are near free on places like eBay. Even MapPoint 2000 I believe had a basic 'territory' function.
R, and highly recommend just using R Studio especially if you are not a coder, is a great and probably better if you are willing to do some of the data preparation lifting yourself, which I think will be the case in any program. Then once the data is prepared you could use a package like RgoogleMaps to do the plotting and adjust the data and visualize it in the same code. If you need a basic intro to R, DataCamp and to a lesser degree Lynda.com have some good intro tutorials on it and then there are numerous blog posts out there about plotting things on maps.
Tableau is a great and versatile program and can do some basic analytics too. It is not cheap, but if you have a limited single purpose use of it and do not mind your displays being public (private link, but if they have the link it can be found) then the terms of service for Tableau Public might work for you (you would need to check).
There is also just doing it in Excel.This blog posting of GIS Exchange talks about using MapCite, BeGraphics, MapLand, and Esri with excel to create maps. I have not used any of these.
Microsoft also lists Power Map for Excel as an alternative to MapPoint available in newer versions of Office 365 but I do not have the latest version with this feature but it looks very promising.
What I have prepared my data in Excel and then used a personal map inside of Google Docs to import the data but this has only provided location plots which I then used a graphics program like Photoshop or even SnagIt to then shade in the areas depending on presentation quality required.