What they are talking about is Resort ID DL31, Grand Luxxe VI, which is in Tower 6 or 5C at NV. The units they are referring to are what Vidanta calls Suite Royal 2 BR suites, which you can find details about at
https://www.vidanta.com/en/web/nuevo-vallarta/grand-luxxe-two-bedroom-suite-royal. Those are smaller than the normal Grand Luxxe suites in a less than optimal location, but have the same resort fees as the normal Grand Luxxe suites. Personally, I would prefer the regular Grand Luxxe 2 BR through RCI Resort ID RB71 for the cost overall, though with the 2 BR spa units (Resort ID D986) you would definitely have the upper floor location and they do appear to have availability in December for the non-Christmas weeks. Between those two, if the points necessary for the exchange are the same, the exchange fee difference is only $100, IIRC what Registry costs, and the resort fee is the same ($950), so I would go for the spa unit, assuming those dates would work. If they both go for 77,000 Wyndham points in December for a 2 BR, using my costs at Bali Hai that would be ~ $350 for the points, $250 for the exchange fee, and $950 for the resort fee for a total of ~$1,550, which isn't bad (~$1,650 for the Spa); the location difference (and certainty) for the Spa units might be worth it for just the extra $100 or so. If they really have Villa availability through Registry, I would probably go for that. The Villa units are about half again as large as either the 2 BR Suite or Spa units, which are both on the same footprint - there are tradeoffs you'd be making, of course. With the Villa, you'd have an extra sitting room with a pull out couch that could be used for another private sleeping as well as the pull out couch in the living room area, so the extra private accommodations might be worth the extra cost depending on your situation with the children and the parent.
As an alternative for comparison, ThirdHome has availability in Grand Luxxe Villa 2 BRs in December for the non-Christmas weeks for an exchange fee of $995, a resort fee of $294, and an underlying deposit value of 6 keys (the ThirdHome exchange currency), which I would value at ~ $900 based on the average cost/key I got this year depositing stays with them. That would put the total cost closer to $2,200, so in my book, RB71 through Wyndham RCI (or D986 through Registry) wins out. Earlier in the year, there are more higher-end unit types available in ThirdHome that I'd go for if it were me rather than going for the RCI or Registry exchange; if you had been able to catch one of the keyless exchanges (i.e., exchange and resort fee only without an underlying deposit), I'd go for the Villa through ThirdHome instead (and did for an earlier December week in RM on the way to Belize for a couple of weeks elsewhere this year).
SFX shows availability in mostly studios in December, though there system for displaying available inventory anywhere isn't great. There are a couple of days that show both 1 BR and studio availability, which would equate to 2 BR availability, but it's a bit quirky.
Tower 1 has Grand Luxxe Suite and Villa units. Punta has the Presidential units that come in 1 BR, 2 BR and 3 BR sizes and sometimes trade in Interval International, but not in RCI or Registry. The major appeal to Punta is the location, not the underlying quality of the set up of the units, which have some design/furnishings issues. I haven't actually stayed in one of those, but have visited folks staying there. You would be quite unlikely to get into Tower 1 through an exchange as it's a fairly popular location for owners to use when they go there.