Last Sept/October I did a two week trip to Hawaii with my wife and three month old daughter. We spent six days on Maui, four days on the Big Island, and six days on Kauai. I like adventure and loved the Big Island, consequently, it was not my wife's favorite.
We did not have any set plans for the Big Island unlike the other islands. Also, with significant hotel budgets allotted to Kauai and Maui, we opted for a condo in Kona near the Kings/Queens market. We did do VNP but was a little limited by concerns of hiking with my daughter en tow. We drove through most of it and took some incredible photos, would love to return and do a night time hike to see glowing lava.
We destroyed a SUV while exploring, the trails on the Big Island are not made for trucks as big as Yukon XL's (or perhaps my driving skills were not up to par). However, being adventurous (for me) and searching for trails and lookout spots led us to some amazing places. Lots of pretty sites. And spending some time at the waterfalls was nice, many beautiful sights to explore.
My wife loved our time at the Mountain Thunder coffee farm. Short but interesting tour, amazing coffee, and a great opportunity to drop some serious money on coffee to ship home. However, we are still drinking it and have never had better coffee.
We do not keep strict kosher so I cannot speak to that aspect. We did not find too many great restaurants (in fact the Roy's there was very bad). Brunch at the Four Seasons was very good and wow is that a beautiful property. We spent a fair amount of time walking the property there and if I could find the right prices, I would love to stay there when we return - prices when I checked were around $700/night.
You drive a lot on this island as it is big. Getting from the Kona side to Hilo is a hike.
The Thurston lava tube was just okay.
I know this is not the most thorough of report, but I must say that the rural and undeveloped aspect of the Big Island was wonderful. When I plan my next trip to Hawaii, it will be the Big Island on the itinerary.