You cannot expect solid suite upgrades an any resorts, especially if they frequented by the Americans (if we assume that vast majority of Plats are from the US simply due to a number of properties -- close to the combined of rest of the world). At least, Lagunamar does upgrade in principle. Say, Westin Cayman does NOT ever upgrade to a suite (not being a SVO). Their sister prop at St Maarten (SVO) does it extremely rarely in the lowest season only. They both don't accept SNAs.
Does anyone know if Lagunamar accepts SNAs? I can try to do a mock booking but if someone knows (Lurkers)?

Ended up making a reservation myself. As expected, no only SNAs were "not available" on spg.com but confrimation details specifically worded it out: "As a villa property, we are unable to offer select SPG(R) elite member benefits including upgrades, Suite Night Awards, 4:00 p.m. late check-out and Your24"

It's hardly a villa in my view: 400 sq. ft studio. Many props call 400-500 sq.ft units a basic room.