I think the road to Hana is over-rated, but I realize it's something most tourists feel they have to do. Route 340 around the NW end of Maui is more interesting in my opinion, but not for the faint of heart.

http://www.bestofhawaii.com/maps/images/maui.jpg

If you make it to Volcano on the "Big Island",(a must see), you can stay at the Volcano's National Park cabins located next to the Namakani Paio campground for about $35 or $40 a night. Make reservations well in advance because the cabins are very popular. The cabins are reserved through the Volcano House Hotel. 1-808-967-7321

http://www.nps.gov/havo/visitor/camping.htm
Aloha