efficient way to create a line of sight

[MaryellenRosebrough]

Interested in an efficient way to create a line of sight between points for 3D Spatial Analysis. In instances where the target and observer locations are flexible and their heights are flexible, it would be nice to have a tool that can assist in finding the line of sight as the current method is the user manually trying different points. The tool could display the best choices from one location to another for possible lines of sight based on different heights for the Observer and Target (point at observer to multiple lines within a polygon at target or polygon at observer with multiple lines within a polygon at target). 

Example: I want to have wireless internet access between two locations. I can create a tower of any height at either location or to the top of an existing building at either location. The exact location on either end is flexible as is the height. I would like a tool to assist in finding the best options vs. the current method of trail and error until you find the lowest (cheapest to build) option. 

Thanks.