This is your answer.
DVC is a luxury, not an investment. Buy where
you want to stay. Buy enough points at the resort you want to stay at for the villa size you want to stay in for the number of days you want to stay there.
You bought Riviera 9 months ago, why not get another couple of stays under your belt before you buy more points? Unless there’s a planned stay in the next 2 years that you will not have enough points for, there’s no rush to add on - Poly likely won’t sell out before 2026, meanwhile, leaving your DVC purchase cash in a CD will help ameliorate any DVC price increases.
Dreams of extended family trips are just that - dreams. Sometimes the stars align & your guests are available & can afford a WDW visit (tickets/meals/getting there is expensive even w/ lodging paid for.) Many times things don’t work out. Someone has an unexpected expense or illness or whatever & can’t go. I’ve owned over a decade & think the stars have finally aligned & I’ll be able to host family in a GV next year, at least everyone has committed & started saving for the airfare/tickets

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AUL was first offered for sale over 14 years ago, it’s still not sold out for a reason. It is a lovely resort, however, timeshares are abundant in the islands & w/out the lure of the world’s most popular theme parks, consumers wanting to commit to vacationing in Hawaii regularly have many options. Personally, my favorite island is Kauai, so I’ve no interest in a timeshare located on Oahu

. My second visit to Kauai I stayed in a lovely timeshare unit I had rented, if I’d had the funds back then I would have happily bought there, but it’s long gone thanx to Hurricane Iniki.