I have heard from several sources that the excursion to Volcano National Park is a "must see" trip, so I'm planning to check it out in October.
Norm, I totally agree about that ... it was one of our favorite outings. We just lucked out when we were at the waterfalls outside Hilo when we overheard some other folks were heading to Volcanoes Park, so we decided to squeeze it in. Consulting my Revealed guide, we got the route and 40 mins later were at the park. I remember telling Art, "We have one hour," so we adopted our "speed tourism" strategy -- see, click photo, 5 min, and back in car. By this, we got to see the steam vents, the crater lookout and the lava tube/rain forest in the course of one hour.
On the drive back, is a huge orchid place where the ship's tours stop (easy to do on your own) and the Macadamia nut outlet (again, easy to do on your own).
By the way, Hilo had the easiest car pickup/drop-off, too ... at the airport, which was easy to get out of and easy to find on our way back. Very centrally located to hit the main streets to get to the sights.
By the way, because we had the shortest day in Hilo (we did not get off the ship till 10 and had to be back by 3:30), I feel like we crammed a lot in. *And* it never rained!