The weather in Kona is great, just got back from my honeymoon there last week, hardly any rain.
If you will spend all your time at the resort and don't mind driving to town or anywhere else, then Kona is a great place. The drive to Kona is about 40 minutes on a good day, more like an hour or more during the commuter rush though. Waimea is about a 30 minute drive inland.
There is something on the big island that you can't see anywhere else, which is Kilauea volcano erupting. We took a chartered boat ride at the southern tip of the island and got to see the hot lava actually flowing into the sea, it was a once in a lifetime escursion.
The only drawbacks to Kona are the traffic, the amount of tourists, and the lack of endless beaches due to the lava. I would imagine the other two Hilton locations wouldn't have those same drawbacks, but it would be a non issue if you stayed on the resort, there is a nice beach there for the guests.
Have fun.
