A info.
The website Skyvector is extremely helpful in locating and determining heights of A's around the US. To use it, go to http://www.skyvector.com
click Charts or TAC (Terminal Area Chart, offers greater detail of big cities) at the top. Select the state you want to look at. This will bring you to a sectional airplane chart for that area.
On either chart, antennas are shown as triangles, and there is a symbol for antennas over 1000' AGL and a different one for under 1000' AGL. There are also symbols for lighted and unlighted ones.
The chart shows antenna is MSL, and then in parentheses below shows the antenna height in AGL.
On every chart, there is a legend to the left which explains the different symbols and markings.
It obviously doesn't cover all the other things to be considered, just heights and locations. Also, there are other databases for A's. I have found this handy, figured I would share.
Thats it.
Be safe,
Jeff