I just made a rez at a non-chain hotel on the site and it seemed pretty straightforward. Four nights for the price of three.
Am I missing any benefits by going that way? Since it's a one-off hotel, there are no elite benefits or anything. If I booked through Virtuoso, I'd get breakfast, but the fourth night is worth more than breakfast for all four for two people (and this way, I won't feel obligated to eat breakfast there).