Too bad the discount is not applicable to the Value Park Garage. I need to park for 8 days in December, and the price (after discount) for Terminal 1 Daily Park Garage is $136. Value Park Garage is $120 (without discount), so I guess I'll stick with Value Park Garage.
BTW, for anyone parking for 1 day (or less), you will have get the greatest discount. It costs only $6 (original price $30) for a full day parking at T1 or T3.