See as many geothermal features with a National Park Ranger as your schedule and planning will allow. National Park Rangers are passionate about the places they are showing you, tell wonderful stories and are a wealth of information. And its all free.
My kids (5-11 years) were able to ask questions and get real answers from people who knew what they were talking about. Many of the ranger led tours also provided information that got them thinking about what they were seeing from a different angle.
For children under 12, keep to the walks and talks which range from 20 minutes to 2 hours. You will be on your feet all the time, bring lots of drinking water to keep hydrated and snacks to keep the troops motivated.