globalbc,
The tour height is a setting in your Google Earth Options and, unfortunately, has nothing to do with the altitude in your path. To change the default:
1. Click "Tools> Options...". This causes the Google Earth Options Window to appear.
2. Click on the third tab "Control"
3. Check the advanced button in the lower left hand corner, directly above "Reset to Defaults." This will cause the window to expand.
4. The bottom section "Driving Directions Tour Options" you can change the behavior of touring a line string path.
Note: you can use the sliders or directly type the values in the text box.
5. Click "OK"
This is a constant altitude for the entire tour.
Here is another post talking about the same thing.
Hope this helps.