I've read conflicting information and am looking for clarification. What's the best route from the Hilton Waikoloa Village to the volcano?

From there it's pretty much on the opposite side of the island with a big mountain in between.
So it really would depend on what you want to see along the way and how much time you have.
We took the route around the south part of the island, passing through Kailua-Kona and the black sand beach. I don't think it'll matter which way you go really unless you are in a pinch for time. That's where the hotel staff can probably give you the best tips.

Aloha, just returned from the BI and saw the lava!! Awesome! Not sure about the route but the road was closed for 7 days and on Sunday when we went they opened it at 12:30 so we were lucky. Got so close too. So call to see if the road is open. The ride we took from Hapuna Prince was long and beware it's winding, up and down, but worth it. Such diverse landscape on the BI. Too see where the lava flows have been is kinda like seeing where a tornado has touched down and done devestation to one house and didn't touch the one next to it. One side is all old lava flows and next to it is almost a lush forest! Anyway, don't know if I am making sense!! Took the Saddle Road and THAT is up and down and winding as well.

Man oh man. I don't travel much but it seems that all the questions are up my alley this evening. You can check my answer to the question on Waikoloa for some other information.

In answer to your query, we went the opposite way. We went north around the island - to Halo - and then started going south to the volcanos. Like I said before, go to the black sand beach if you can. It was very cool. Secondly, start early in the day. We stopped at a local drive thru in Halo that had the best local food. You can see it from the highway. Lots of cars in the parking lot. It was great.

The change of scenery from one side of the island to the other was unbelievable. It is hard to believe you are on the same island (desert to lush tropics to volcanos all in one day)

In regards to leaving early and breakfast, we left early too and ate a great breakfast at Aloha Angel Cafe. It is just south of Kona in Kainaliu, it's a restored theater and all homemade food, even to die for bakery. Took some for a snack down the road. Stopped at Black Sand Beach as well, special treat of a sea turtle sunning it's self on the beach! Wonderful day.