Masterpark Lot B is directly across the street from the airport. It is so close, but is still pretty affordable, especially if you can take advantage of discounts. I pay $9.95 a night with my discount from work. There is always a shuttle waiting that will get going to the airport less than five minutes after you drop off your keys. Even if you miss one, they have enough shuttles in service at any given time that the next one is not long in coming.
I hate waiting at the airport, so I usually aim to be at the airport about forty-five to fifty minutes before my flight. For international flights, I might try and get there an hour and a half before the flight. Using this strategy, I have very little wiggle room and can't afford to miss my flight because of slow shuttle drivers. This is why I use Masterpark Lot C. Not only are they mere hundreds of feet from the airport entrance, they also have quick and efficient service and they're inexpensive to boot! (I get a corporate discount that lets me park there at $9 a day.)
When you come back home from your trip, you can call them on your cell phone after you've deplaned, as you're leaving the airport. Don't call too soon because it rarely takes them long to get there. You don't want to risk having them pass on by without you! Oftentimes, I don't call at all because I know I'll spot one of their shuttles as I'm crossing the skybridge. If you hurry at this point, you can totally make it down the stairs in time to flag the driver. They're great about pulling over and getting you onboard.