The Thomas A. Jaggar Museum has public displays, including seismographs showing the activity at sites around the island. There is also a small gift shop inside the museum. There is a good public restroom on the way to the entrance to the museum. The Hawaiian Volcano Observatory is a research facility that is not open to the public. This site is on the lip of Kilauea Crater.
Crater is the prominent feature.
This is the view that most visitors rush to see and it is indeed worth a leisurely look. Viewing the opposite way, from the parking lot away from the museum, you may be lucky enough to see the full aspect of Mauna Loa. Both of these are active volcanoes. If you look along the lower slopes of Mauna Loa, you will see a light green patch. This is a grazed area outside the park boundary.