Yellowstone and Hawaiʻi. These systems a well known for producing large volumes of magma through time and leaving chains of volcanic features in their wake, although they do so in very different ways.
Yellowstone's volcano is not extinct ... out for miles beneath us and a few little hills to the north—old lava domes. But I can't follow the caldera rim visually because much of it is beneath ...
What might happen if Yellowstone were to erupt is difficult ... would likely produce lava flows or domes, which, although dramatic, would be less destructive and pose little threat to people.