No way SLC is similar to Denver, Boston, and Vegas.
City population really has nothing to do with it. Boise city has more people that the city of Salt Lake City. That's why I think tourism, major business HQ's, and airport, are the 3 things you look at.
Here is how I look at it...
Top Dog Major: New York, LA, Chicago, Houston, Philadelphia, DC, Boston, Seattle, Dallas, Miami, Atlanta, San Francisco, Las Vegas
Major: Denver, St. Louis, Honolulu, Charlotte, San Antonio, Baltimore, San Diego, Portland, Kansas City, Orlando, Phoenix, Cleveland, Detroit, Minneapolis......etc.....
Midsize: Austin, Salt Lake City, Sacramento, San Jose, Raleigh, Tampa, New Orleans, Nashville, Memphis, Oklahoma City, Milwaukee, Indianapolis.....etc.....
Small: Omaha, Albuquerque, Reno, Savannah, Myrtle Beach, El Paso, Boise, Colorado Springs, Provo, Madison, Wichita, Fargo, Knoxville, Syracuse.....etc....
Extra Small: Santa Barbara, Bellingham, Burlington, St. George, Palm Springs, Gainesville.....etc.....
Extra Extra Small: Vail, Monterey, Park City.....etc.....
Then maybe we're all wrong when it comes to judging this stuff, LOL.
http://en.wikipedia.org/wiki/Alpha_world_cities#Alpha_world_cities