I always qwikpark. Right now their coupon special is $8 a day or $50 a week. I was lucky enough to get a coupon good through 12/31/12 for buy one day/get one free and I do a lot of weekend trips so that is great for me. They also do AAA discounts.

Link is:
http://qwikpark.com/wp-content/uploa.../QPexpcoup.jpg

Even if on site was the same price I would still park there since you don't have to drive around looking for a space and then lug your luggage to and from your car. The attendant will tell you as soon as you pull in what row to park at and they pick you up and drop you off right at your car.

If they tell you to park in a certain row and there is parking at the fence right before you turn at that row, grab the spot by the fence The shuttle will still pick you up and there and you will get dropped off a lot faster normally if it's a full shuttle returning.

If you aren't a-list, allow extra time for security, I have seen the lines pretty long in the north terminal before for the non-priority lines.