If you're heading to Hawaii's Big Island, then one of the first questions you may have is, 'Where is the lava? I want to see the lava! Wait, or is it magma?' First, yes, typically it's lava you're looking for - lava is anything that's erupted from the volcano (to the surface) and it comes in two flavors, Pahoehoe and A`a. You can read more about the two lava types on our Hawaii Geology page. If it's still within the volcano, it's known as magma.
Now, to answer the question of 'where.' Well, the answer to that question depends on the mood of Pele (the Hawaiian Volcano Goddess). And Madame Pele is very unpredictable. You could just as easily witness lava flows chewing on Chain of Craters Road as you could view a steam plume from afar. It is a living, breathing volcano with a mind of its own. The good news is that Hawaii Volcanoes National Park is open 24 hours a day, so your chance to see glowing lava (from near or far) is pretty good when it's dark. Just look for the red glow. Currently Kilauea caldera has a large gaping hole that lights up the park at night (it has also shut down a portion of Crater Rim Drive due to safety concerns). If you come to the park envisioning a massive cauldron with lava, you may leave disappointed. Currently most of the lava, well magma really, is flowing underground into the ocean through a series of lava tubes. The current eruption site is not easily accessible at this time. Currently Kilauea caldera at Halemaumau is your best bet to view the glow of magma.
Even if you don't get to see any flowing lava in person, Hawaii Volcanoes National Park and the Big Island are well worth the time. Another great option is to take a helicopter tour over Pu`u O`o for a look into the bowels of the earth. But, that too could change tomorrow. Lava has a mind of its own.
Check THIS SITE for updates on lava flows and Kilauea activity.