More for my benefit than anyone else's, I've compiled these resources on the August solar eclipse.
Use Google Maps street view to figure out where exactly you're going to park and stand.
The total solar eclipse will last just a few minutes. Enter the zip code of your observation site in this calculator to determine exactly when the moon will cover the sun (this information is also available on the map above).
Eyeball this map, which is colored by average cloud cover.
Then use Weatherspark to look at historical cloud cover for your particular location. Drill down into the cloud diagram and select August 21 to get hour-by-hour historical predictions (example: Depoe Bay, OR).