I'm planning to go to the Netherlands on August 4th and drive around for three days before going to Germany. Are there any fun places to go? How can I rent a car at a good price ?

You're timing it right. There's Amsterdam Pride at the beginning of August (before the 6th), so you can spend a day in Amsterdam, and then the windmills are worth a visit (depending on where you're staying, they're a bit further north). Pride is a time for everyone to have fun abroad, and Amsterdam Pride is actually a festival for straight people (laughs). Amsterdam also has the Red Light District, but of course it's up to the parents whether they want their kids to be exposed to it or not (to be honest, the earlier they're exposed to it, the less repressed they'll be later and the less likely they'll become even more curious, we're all people who have been through it). And if you have kids, you can go to Madurodam in The Hague.