For want of anything better to post, here's a breakdown of if I've been to the most populous 100 cities in the US, and if so for how long:

More than a week in total: Philadelphia, Washington, Boston, Orlando

More than a weekend, up to a week: New York, Chicago, San Diego, San Francisco, Nashville, Atlanta, Tulsa, New Orleans, Anaheim, Pittsburgh

A weekend to a longish weekend: Los Angeles, Houston, Austin, Columbus, Indianapolis, Seattle, Las Vegas, Detroit, Baltimore, Kansas City, Cleveland, St. Louis, Buffalo, Madison

In for the day: San Antonio, Virginia Beach

Less than a day, including being in transit only: Dallas, Jacksonville, San Jose, Charlotte, Denver, Long Beach, Oakland, Minneapolis, Henderson (NV), Newark, Toledo, Norfolk, Richmond

To the best of my knowledge, I've never been: Phoenix, Fort Worth, Oklahoma City, El Paso, Portland (OR), Louisville, Memphis, Milwaukee, Albuquerque, Tucson, Fresno, Sacramento, Mesa, Colorado Springs, Omaha, Raleigh, Miami, Bakersfield, Tampa, Wichita, Arlington (TX), Aurora (CO), Honolulu, Stockton, Riverside, Lexington (KY), Corpus Christi, Irvine, Cincinnati, Santa Ana, Saint Paul, Greensboro, Lincoln, Durham, Plano, Anchorage, Jersey City, Chandler, North Las Vegas, Chula Vista, Gilbert, Reno, Fort Wayne, Lubbock, St. Petersburg, Laredo, Irving, Chesapeake, Glendale, Winston-Salem, Scottsdale, Garland, Boise, Port St. Lucie, Spokane, Fremont, Huntsville

It's possible I've been in a few of these, even briefly (Chesapeake and Jersey City seem most likely). It looks like I could knock off a bunch of these by driving around the Metroplex and the Phoenix area for a couple of hours.

 As a sort of follow-up to the post about cities I've only been to through their airports, here are the US states I've been to for less than 24 hours.

Arizona - when we visited the Hoover Dam, the wife and I walked across from Nevada to Arizona. There being nothing on the Arizona side but barren landscape, we maybe stayed for two minutes. Hands down the state I've been to but spent the least amount of time.

Colorado - as mentioned in that other post, I've only been to Colorado due to flying through Denver once. 

Idaho - on our road trip from Salt Lake City to Chicago, we went through Idaho pretty much so we could say we'd been there. We overnighted in Pocatello, and got to see both some of the Idaho State campus and the much improved city flag. 

Kansas - on a visit to Kansas City, some friends and I drove over to Overland Park to visit the NCAA headquarters. It was closed. We drove back to KC.

Kentucky - the sum total of my Bluegrass State visitation is time spent connecting through the "Cincinnati" airport in Covington.

Minnesota - on the same road trip where we stopped in Idaho, we stopped overnight in Minnesota mostly because the kids wanted to go to the Mall of America. This is probably the state on the list in which I've spent the most time.

West Virginia - all of my time in West Virginia has been due to Scout trips. In high school we cut through one of the spiky bits when driving from Shenandoah National Park to Gettysburg. As an adult, I spent an afternoon in Harpers Ferry while chaperoning a Scout trip to both Gettysburg and Antietam.

And while we're at it, the countries I've been to for less than 24 hours:

Bahamas - stopped at Disney's resort island while on a cruise, so no real experience with Bahamian culture or people at all.

Germany - one of our visits to the UK had us fly home through Frankfurt.

Mexico - same cruise as the Bahamas stop, spent a day ashore in and around Cozumel.

Turkey - flew through coming and going to Italy

Vatican City - same Italy trip, spent one of the days at the Vatican Museum and then in St. Peter's square while others went into the basilica (I passed as my knee wasn't up to standing in line for a couple of hours).