I thought Hawaii was our 57th state...
I did what I would modestly call a FANTASTIC photo gallery about the volcano on Hawaii from my Pride of Aloha trip in 2006. It is here:
Let me say this - hiking over the volcano is extremely grueling and dangerous. The oxygen content of the air diminishes the deeper in you get (replaced by sulphar) and by the time you reach lava you may be gasping for air. I did, so I know.
I hiked for over 2 hours round trip and did not reach flowing lava, but I did see a hot hole (see my photo gallery). Here is the thing...
The lava landscape is constantly changing - and the terrain is very rough. I twisted my ankle and almost didnt make it back.
Depending on the conditions when you get there, I highly recommend you ask what you might see on a guided tour towards the lava flow. Chances are you canNOT reach lava flowing on foot, but if they say you can then go on a GUIDED tour or you may get lost. At the least you will see more in less time by not getting lost. There is no trail, the cold lava is like walking on hardened moltened glass.
Having said that - a helicopter is the ONLY sure way you will see tons of hot flowing lava up close up with your own two eyes. If I had it to do over again I would spend any amount to take a helicopter tour rather than take the hike. They will get you over the lava in a matter of minutes, while a walking tour will get you to a minor flow not worthy of comparison to where the biggest flows are breaking out.
I have taken two helicopter tours - in Bora Bora and in Alaska to a glacier. On the second one I told the pilot I get airsick and he kept it level, so I did not feel nauseated at all. if you say nothing these guys may give you a roller coaster ride, but just know that is not an inevitability.