A "W" for SLC would be great, but I agree with the guy above that Aloft would probably be a better fit. Westin is more conservative and would be more likely, and contrary to a comment above, they earn every 1 one of their 5 stars for comfort & luxury, and SLC doesn't have a five star hotel at this point. Grand America is a 5 "diamond" hotel rated by AAA, which really wouldn't fly with hotels in London and Paris. The star system is an internationally accepted system for rating restaurants, hotels & resorts around the world. Starwood is launching a new brand of 5 star luxury hotels called "1" Hotel & Residences, with the first to be built in Seattle and then followed by Paris I believe. It bills itself as the first 5 star luxury hotel that is eco friendly and environmentally sustainable. The link is below with a rendering and description. Keep us posted on what brand is going to be built in SLC, and no matter which it is, it will be a great addition to the city!
http://www.djc.com/news/ae/11183489.html