If you are going during winter months and leaving on a Saturday or Sunday, consider the Westin. It's not cheap, but they have a weekend park-n-fly special. Around $160 plus tax for the night, which includes 8 days of valet parking. The best part: you can go from your bed to your plane without having to go outside! When you get back, they will bring your car right to you, again without you leaving the terminal. It's maybe an extra $60-$80 over what you'd pay for an off-airport park-n-fly, but your car stays in covered parking (no snow!) and it's a nice way to pamper yourself and get your vacation off on the right foot.
They do not seem to have '06 park-n-fly rates yet, but I would expect them soon.