Originally Posted by
Wiirachay
I park at the Herdon-Monroe parking lot along the Dulles toll road. The 5A bus swings by every hour on the weekend and every 30 minutes during rush hour. Did I mention that parking is free?

Bus costs $3.00 each way.
The 5A schedule is at
http://www.wmata.com/timetables/dc/5a.pdf
Note that the cash fare is now $3.10. The frequency you quoted is only partly correct - the bus is every 60 minutes on weekends and holidays, but it is every 40 minutes on weekdays (regardless of rush hour or not).
As for extended parking at the Herndon-Monroe Garage, according to
http://www.fairfaxcounty.gov/connect..._p_r_const.pdf
"Overnight parking is prohibited in the garage." I'm not sure about enforcement of this, but I wouldn't risk it.