Mine are 4 and 7. They can stay up until 9 witout a problem, even though they are up at 6:00am weekdays. They don't nap. However, I have no idea how they are going to handle days on end of theme parks. My plan is to not tell them about the fireworks. That way, they won't be disappointed if they miss them. We'll try to keep them out doing something active and fun that evening after supper - maybe in a park or maybe not - but something so they don't get a chance to start winding down. If they look energetic enough by the time we need to head to the fireworks, we'll go. I'll probably end up getting specially interesting junk food around then, to keep them interested and awake. If however they are getting sleepy/cranky in the evening, we'll skip it.