We were recommended to ShakaMauiAudioTourGuide by a friend, and we did the Road to Hana, Maui. It was scary! The music did get annoying on the way back so we would pause it, and then the tour guide would start back up again automatically.
You should preview the spots on the tour 2 days before you plan to go, and make your reservations. Also, do your research—certain days of the week may be less crowded.
If we knew that we would preview the spots on the listing ahead of time the night before, perhaps we would have booked the black sand park reservation ahead of time. Unfortunately, we passed the black sand park and did not have a reservation, but felt frightened enough of the road that we did not go back. We went all the way past Hana and did not reach the seven springs. We appreciated the reminder to turn around, providing us a time estimate for the way back. We were able to visit a public waterfall that people were swimming in. It was very far to get there. Heading back west toward the OGG airport on the road to Hana, was tricky since the stop sign for the one way roads favored the East bound traffic as they could come closer to the stop. It is dangerous to go in reverse.
Overall, we survived thankfully and mostly in part a great thanks to the tips on tracking time and ensuring we have enough drive time for the journey back.