I stayed at the Conrad in Punta Del Este and got an Gold upgrade to a large room on the top floor and Hilton points. So unless things have changed this year, they are definitely part of Hilton.

If you like late night excitement and great beach action, you should drive right through Montevideo and head for PDP.

I think I posted a trip report a year and a half ago so you should be able to search it for hotel and restaurant info. Let me know if you need more details.