Salt Lake City really is worth a trip! I have been to many cities in the US but none of them were so clean and seemed so laid back! Salt Lake is surrounded by mountains and the Great Salt Lake which are perfect ingredients of a beautiful setting!
Temple Square is the heart of downtown SLC. The Temple is beautiful but as it is a sacred place for the Mormons it can only be visited from the outside. All other buildings can be visited and are for free.
The Tabernacle has a fantastic acoustic and is home of a famous choir. I would highly recommend a look inside when there is an organ or choir practise.
If you pass by Utah’s Capitol Hill you get to Ensign Point. It is only a 1mile round trip which is rewarded with a great view over the city and the lake.