Tough decision. I also would be tempted by the offer. We took advantage of one of these some years ago in Maui at Westin Villas when it was still SPG, and it wasn’t too painful, but I have heard the Marriott ones are more agressive. At the time, it was our only way of getting to Maui, so a different situation.
I think your points value currently is very, very good for Hawaii and if as you say, you have nothing else on the horizon for using those points, I would stick with what you have. If you had other trips planned that you needed points for it may be different. Another option would be to extend your trip! Stay an extra 5 days. Actually, that’s what I would do, lol.