To answer OP's question, though -- the pull-down "Destinations" menu on that page appears to contain a full list of the properties. Currently:

• United States
•  
  • Arizona
    • Sheraton Desert Oasis
    • The Westin Kierland Villas
  • California
    • The Westin Desert Willow Villas, Palm Desert
    • The Westin Mission Hills Resort Villas, Palm Springs
  • Colorado
    • Sheraton Lakeside Terrace Villas at Mountain Vista
    • Sheraton Mountain Vista
    • Sheraton Steamboat Resort Villas
    • The Westin Riverfront Mountain Villas
•  
  • Florida
    • Sheraton PGA Vacation Resort
    • Sheraton Vistana Resort
    • Sheraton Vistana Villages
    • Vistana Beach Club
  • Hawai‘i
    • Sheraton Kauai Resort
    • The Westin Kā‘anapali Ocean Resort Villas
    • The Westin Kā‘anapali Ocean Resort Villas North
    • The Westin Nanea Ocean Villas
    • The Westin Princeville Ocean Resort Villas
  • South Carolina
    • Sheraton Broadway Plantation
• Caribbean
  • The Bahamas
    • Harborside Resort at Atlantis
  • U.S. Virgin Islands
    • The Westin St. John Resort Villas
• Mexico
  • Cancún
    • The Westin Lagunamar Ocean Resort
    • The Westin Resort & Spa, Cancún
  • Los Cabos
    • The Westin Los Cabos Resort Villas & Spa
  • Puerto Vallarta
    • The Westin Resort & Spa, Puerto Vallarta*
  • *Resort Hotel