I can confirm as of Feb. 2020 that the JW Marriott Nashville lounge is closed on weekends, but for Platinum Elites and up, a voucher for breakfast in the Stompin' Grounds Restaurant is provided. This voucher is for the breakfast buffet (though card said continental breakfast), which is quite nice and is valued at $24. Weirdly, our server did not take our voucher when we presented it, and later brought us a bill for $52+ ($48 + tax). When asked, she said leave the voucher and we were good, but it was a little confusing. I guess the bill provides the option to tip and either charge a card or your room. We left a cash tip and the voucher.

The lounge breakfast (on the 33rd floor, with a beautiful view of Nashville) was also quite nice and very similar to the restaurant buffet but with less hot items (just scrambled eggs & bacon) though it also had smoked salmon with several accompaniments. There were some decent snacks and beverages in the lounge as well but we did not make it up there for hors d'ouevres or desserts.