The folks at Blue Hawaiian will give you a great tour of the volcano from the air. They even record your flight and you can purchase the dvd, so you can share this great experience with friends and family back home.
While you will find black sand beaches on the other islands, I like the one on the Big Island the very best.
Punalu'u is where you will frequently find sea turtles lying on the beach sunning themselves. It's the best I have found for being able to see these awesome creatures.
Regulations require you not get closer than 50 feet, but that is close enough to view without disturbing them.
Where else can you get your picture taken with a large turtle?
The Two Sides Of The Island
Like all of the Hawaiian islands, the Big Island has two sides.
Kona is the dry, desert side of the island, and Hilo is the wet, tropical side. So when planning your Hawaii Big Island vacation, make your reservations on the side of the island that will suit you best.
I have been to both sides of the island, and while both are beautiful, they are vastly different. Tropical vegetation is found on the Hilo side, but remember, tropical vegetation requires rain.
Kona is the flip side of Hilo. Perpetually warm sunny conditions creates a lack of vegetation, giving Kona a more desert feel.
Visit here for some great options and prices on Hawaii Vacations
While you will find black sand beaches on the other islands, I like the one on the Big Island the very best. 
