This is a new parenting approach that Gana has taught me: I used to think that treating all the kids identically was essential, hence I wouldn't think of going to Six Flags unless all could go. But now we're doing more one-on-one activities, to let each child know how special they are. And to my surprise, the kids seem happy with that. Since each child is different, they usually want to do very different activities anyways.
One Six Flags life-saver: bringing along water bottles. I can't believe how much water we drank, and although the food/drink prices are outlandish, the food stands are happy to load you up with ice water.