This web site provides some tools that are unavailable in the free version of Google Earth.
The generalize tool reduces the number of points in a line. The buffering tool creates buffers around points, lines, or polygons. The area tool calculates the area of a polygon. The answer is in square meters, but can easily be converted to acres. I haven't quite figured out what the overlay tool does.
To use these tools you download an element as a kml file, then upload it to the web site. It's not as convenient as a built-in tool, but it is free!