You can take a helicopter trip around Kilauea volcano leaving from either Kona on the West coast or, as I did, from Hilo on the East coast. It's definitely worth the price, if it's not cloudy or foggy.
At the moment, the main caldera at the top of Kilauea is basically dormant, but there is activity at the Puu Oo vent on the Northeast slope of the volcano. Once you get to the vent, you might be lucky enough to have a view inside the crater and see its active lava pools, depending on the cloud and smoke cover, and on how much activity there is at the time.
For some reason, the lava coming out of Kilauea mostly doesn't flow on the surface of the lava field. Instead, it flows underneath in very long lava tubes, appearing on the surface only as it nears the ocean. Even when the lava ceases to come out of the mountain, the lava in these tubes continues, resulting in hollowed out lava tubes, like the Thurston lava tube near Kilauea's main caldera. However, the lava is fragile, and sometimes the roof of the lava tube collapses, resulting in a "skylight". If lava is still flowing through the tube, then you can see the lava flowing through the skylight. This lava eventually exits the tube near the ocean, and you can see that the lava as it flows into the ocean, creating new land and clouds of steam from the boiling seawater.