One thing to remember when you're day tripping is that you still have to get to the airport, go through security, catch the 1 hour flight, do a full day of activities and back to the airport you go for a return flight and drive to your hotel. Also, please keep in mind that some tour companies don't pick up in Kapolei - only Waikiki. So you may have to find an alternate route to and from the airport to meet your tour group. You're looking at a 13 hour day minimum, maybe more depending on the traffic to and from Aulani. Please make sure you check the itinerary and schedules of pickup and drop-off times to get an idea of how much time you'll be spending.
Having said that, I did the Volcano eco-tour though Discover Hawaii Tours, and it was great. They do have a package where you could be flown over, but I was already in Hilo, so I didn't need to fly anywhere.
In terms of the lava tubes on Maui, you have to drive the infamous Hana Highway in order to get there or pay someone to do it for you. With all the twists and turns, it can take you hours just to get there. Ignore the GPS because it can't account for how many times you'll have to flow down or move to the side to let someone pass. It takes 3 hours each way from West/South Maui. I'd stick with the BI if you're only trying to do a day trip for lava related reasons.
