We went this August. Beyond amazing. The kids ended up doing the young scientist program - cheap, educational, and the kids loved it. It helped that there were geologists mapping the geysers the day we did it. They spent a lot of time impromptu teaching my kids and answering lots of questions. if he is interested in volcanoes he would love this.
The older kids (13) had to form a hypothesis about if they think the supervolcano will erupt again. There may have been a time frame for it(i was helping the younger kids so the teens worked on it on their own). I know they had infrared thermometers and had to measure temperatures of hot springs, geysers, mud pots, etc. it was fun ( but i am a nerd).