Volcano House is a nice place to catch breakfast as you are getting ready to explore the volcano. This is an all you can eat buffet located inside Volcano National Park. There is also a giftshop and snackshop here so you can stock up on water before setting off on a hike.
You can't beat the view here, as you sit in front of a wall of windows overlooking the big crater of the volcano. The food is just so so, but there is a good variety and since restuarants are a little scarce up here, this is a good bet. You can also enjoy lunch and dinner here, but from my experience breakfast is the best bet. They can accomidate large groups, so that is another thing to consider. You will see many class field trips come through. I like to go here everytime I visit and sit in front of the window and contemplate my trip and what my plans are for this exploration.