I love the Big Island. I prefer the Hilo side because it is rain foresty and green, much more so than the Kona side which is a desert. But you should drive around the whole island. I rent vacation rentals near Hilo. Here is a list of my favorite things on the island:

- Volcanoes National Park (Hilo Side): Hike the Kilauea Iki Trail (amazing). Hike the Thurston Lava Tube (at the end there is a fence that says to stop, jump and hike to the back where you will see an evil villain's lair). Try to get close-ish to the current live lava crater around sunset and see how much orange light it gives off. You'll have to ask about that at the information center.
- Beaches: I liked the hike to Green Sand Beach (Papakolea). Black Sand Beach (Punaluu) is really cool and there are usually a bale of turtles sleeping on the sand.
- Waterfalls (Hilo Side): Uma Uma Falls is how I picture the Garden of Eden (it's tricky to get to, BM if you want directions). Pee Pee Falls is fun to see and take a picture with the sign. Rainbow Falls in downtown Hilo is pretty impressive too and easily accessible. Hike and swim in the pools above Rainbow falls as well.
- Snorkeling (Kona Side): Almost any beach on the Kona side is awesome for this.
- Hot Springs: Ahalanui Park (free and my wife's favorite place on the Big Island, super chill). Isaac Hale Park is about a mile farther down the road and it also has a cool Hot Springs to swim in (Pohoiki warm
springs). Check out both.
- Best Lava Tube (Hilo Side): Kaumana Caves Park. It has two sides to choose from, go left. The is a place deep in the lava tube where it has caved in. You can climb out and hike back on a trail that leads back to the parking through some forest areas.
- Astronomy (Middle of island): Find out the night close to new moon and the least cloud cover and head up to the ranger station on Moana Kea an hour after sunset. They have several large telescopes set up and it is an amazing and educational experience. It is pretty high in elevation and very cold so pack a pair of pants and a jacket if you go here. They also have hot chocolate and soups for purchase.
- Chocolate Factory Tour (Kona Side): There is a chocolate factory/farm that does tours in the morning twice a week. It's pretty awesome and you get to sample the goods (ask the try the cacao placenta). http://ohcf.us/tour
- Random (north side of island): If you have time check out Waipio Valley. It's gorgeous.