Some suggestions:

More control over graphics settings. A terrain detail slider and a fog distance slider. Also, time of day and weather controls would be slick. A particle system would be stunning. With a particle system tied into a weather database, like weather.com or accuweather.com, or any number of the US government weather sites, if it was snowing in Ohio it would show particle snow in that area if you had weather effects turned on. It would be nice to have a seperate cache for vertex data (Such as terrain and buildings) because as we all know mountains will always be there, so even if the database is updated, the mountains will be the same shape. (Would reduce download transactions with Google and save everyone a little money.) While we're at it, specularity thrown on large bodies of water would look great.

Measure doesn't take into account height. A little checkbox in measure to, "Calculate height" would be nice, followed by a popup warning, "Notice: Height data is not totally accurate. Your results will vary from actual height distance."

Third party GPS device support would be a nice addition, so if I'm on a laptop on a satellite Internet connection or WiMAX, GoogleEarth would have a, "YOU ARE HERE" button which when clicked grabs the GPS data from the GPS device and shows you exactly where you are.

You guys should hire me.