Volcano is a good 1- 1 1/2 hour drive from Hilo and there's a lot to see there. Hilo doesn't have a whole lot going on ( I used to live there) Kona is a LOT better. What the Hilo side does have is an area called Kalapana (south on the way to Volcano but a little detour towards the water) which is incredible; there's a road that winds through the jungle and takes you to a natural hot spring on the ocean. On the way to the hot springs is the "lava tree park" where an old lava flow made its way to the jungle and up into hollow trees; after the trees burned up there were these pinnacles of lava rock left. Local food is good in Hilo, gotta find the hot malasada stand under the banyan tree on Kilauea st...I think, its been a while. A malasada is a kind of Portuguese warm donut, bad for you but stupid good. Hilo is incredibly wet, bring an umbrella.