OK, I think some of the posters need to realize there are 2 distinct types of parking:
free self parking - usually a 3 hour limit (the BoardWalk I think can vary because they have the nightlife area there that draws in non-resort guests). If you self park at a resort that you aren't eating or shopping at and are there for longer than 3 hours, you are breaking the rules and potentially taking a space from a paying guest of the resort.
$7 valet parking (deluxe/DVC resorts only) - no time limit, you are not taking a spot from a guest, as they can always drive your car to a different lot. Note too that it's $7/day - so you pay at the first resort and then can valet park at any other one the same day for no additional charge (do tip though!). If you are touring the resorts, that is the way to go.