As I mentioned here, I am planning a simulated cross-country flight. To prepare for it, in addition to reviewing the sectional chart, I thought Google Earth could be a useful tool. It sure is! In GE, simply go the the area of the flight, set the view altitude to about the level of expected soaring flight, and set the "tilt" down to nearly horizontal. Then you can zoom around and see what the landscape is going to look like.
Tilt back up, then look at the ground to search for (hopefully) landable fields. The detail is not sufficient to really look for obstructions, wires, etc., but it can give some idea of the size and texture of the field. By looking at the size on the screen of my usual landing area, I can estimate whether a potential field is large enough, though I can't really see fences etc.
GE also has some distance-measuring tools. (I've used them in the past, but not yet in flight planning.) It can calculate a straight-line distance between two points. So you could use it to find the distance to a landing spot or turnpoint.
A web site called FBO Web has some (so far free) resources you can layer on GE.
- Sectional charts! It overlays your choice of charts onto the GE images. If you're viewing in 3D, the chart is mapped onto the topography. You can use a sliding bar to change the transparency of the sectional info vs. the topography. So you can really see what the ground under the chart is going to look like.
- Airspace. This one overlays the boundaries of the special use airspaces on to GE. They're in 3D, so you can view over, under, around, and through them. They seem to be accurate, but incomplete.
These layers can coexist in GE at the same time. So you can get a composite view of topography, roads (with names), sectional chart, airspace, whatever you want - and view it from all angles!