The best part for me is that it's not just a big city with commerce dominating the landscape. It is chock full of Pioneer History. Of course, all that pioneer history is intermixed with LDS Church history since the pioneers were Mormon, but that makes it all the more interesting.
The following shots were taken from the 26th floor observation deck in the Church Administration building. The views of the Valley are breath taking. Free, free, free.
Salt Lake City also houses THE best pioneer museum (PIONEER MEMORIAL MUSEUM on Capitol Hill) I've ever seen. If you are in the area, you must browse around. Admission is free and they sell the best bag of honey taffy ever, for a mere buck. There are 5 floors of artifacts; pianos, medical equipment, navigation and transportation equipment, clothing, everyday implements, photos, toys, Indian artifacts. The list is endless. They even have a stuffed two headed lamb. My kids loved it, and I wasn't able to spend enough time there.
Salt Lake City is incredibly clean, and you can always count on manicured grounds and amazing flower beds.
Don't forget to stop at the Family History Center and see how fun searching for your ancestors can be, and get an idea of the immense scope of the operation. The Lion House tour is fun if you don't have little twin destructo's, and the Joseph Smith Building is worth a walk around. It used to be the Hotel Utah and boasts some pretty splendid architecture.