WendyF wrote:
> ...preferably a weekday in August or September

Wendy, Ken is right about swapping permits. However, since you are interested in a day hike mid-week in August or September, you can get a no-show permit free just by showing up at the Visitor Center where you pick up permits.

Look at last year's Unused Whitney Permits - 2009, and the numbers of unused permits for day hikes. Pretty much any mid-week day, there have been permits available for day hikes. The no-shows become available at 2 PM the day before the hike, so if you are at the VC at that time, your chances are very good. (And they're free!) The unused numbers are what is left at the end of the actual hiking day.