Aloha, Kona has a few trail type runs between the town and the airport. Most of them are hot and dry beach access roads. Even though it is pave Alii drive is my fave run in Kona as it is fairly flat and a beauty.
Volcano has a ton of trail runs, but you need to carry your own water. The Volcano National Park area is at about 4100-4500 ft and can be pretty cool even in summer. There are a bunch of B&B up there to stay at and they actually have a pretty good Thaifood place up there. Now if you like 60's flashbacks stop in Pahoa between Hilo and Volcano. Every old and young hippie and some that wern't even alive in the 60's live there. Good Mexican joint there. Enjoy G

PS Check out trifind.com for the Peaman race series. They are in Kona and cheap(like free sometimes) and a great time. Kona Brewing is the place to eat and cool off in Kona.