Since he likes RIV, I suspect he could be fond of GF/VGF, too. Both are elegant, IMO.
The GF lodge rooms (which is what Big Pine Key will have despite their new "resort studios" label) are larger than most other standard resort rooms. The original villas are pretty sizable, too.
The
YouTube resort tour by 4K WDW gives a really good overview of the GF grounds if you're not very familiar with them. Bonus is there's no music, only ambient sounds. You feel as though you're actually there, which might win him over to VGF.
The catch if you may be thinking of a stay anytime in the next year is that both VGF1 and BPK are close enough to the Poly Tower site that construction noise could be noticeable.
Because the GF and VGF both are $$$$ and points pricey, it's likely to be less crowded than Poly at all but the busiest times of year. We generally have stayed at one or the other the third week in November and have found either rather peaceful. Haven't stayed but one night then at Poly, way over in Pago Pago, so can't reasonably compare.
The Poly seems to draw lots more families with young kids. The GF generally appears to appeal more to adults in our experience.
Not much help, perhaps, because I'm completely in love with the GF and VGF. No way the Poly is the GF's equal or close to it, IMO. You, however, may really love the place. Crowd-schmowd. If you love the Poly, buy there. True love enables dealing with petty inconveniences like crowds.