Hyde Park is really the only park that's real close to Boston, otherwise you're taking a 30 minute car ride out of the city. Wouldn't necessarily recommend Hyde unless you're with multiple kids, which it sounds like you won't be. Boston is pretty small, so you can find spots by just riding around, but there's certain spots you don't really wanna go near by yourself, not that they are THAT dangerous, but they're not to accustomed to scooters.