The points are probably worth $350-700 depending on how you redeem them. Only you can decide if you want to pay the cash (don't forget to add in costs while there) and take the time to go on the trip. My recollection is that Turtle Bay is relatively isolated on the north side of Oahu, FWIW.

I also am suspicious of "United agreed to honor a stacked mile promotion I found" in terms of making sure the points actually credit in the end.