I love, Love, LOVE wearing heels......but not to the parks! If you are committed to wearing them, there are a couple of brands out there, sorry I don't remember the names, that are starting to put air soles or gel in the soles of their pumps/sandals under the ball of your foot. I would think this would make wearing them for extended times a LOT more comfortable. Might be something to look into!
One new line is by Cole Haan AIR - Not the original Cole Haan shoes but the newer line called AIR. They joined forces with a shoe engineer from Nike (hence the name Air) and there is air/support built into the shoe, even though you can't see it. It was featured on one of the programs about shoes hosted by Stacy London from TLC's What Not to Wear. Of course, because they are Cole Haan, most of them run into the hundred(s) of dollars. I haven't seen a pair that I thought was really cute - yet.