While I'm not ordinarily a fan of Las Vegas, it is hands down the absolute best place for conferences, logistically. It's a 10 minute Uber to get from the airport to the strip. Tons of hotels on the strip. If the conference is at one strip hotel and you are staying at pretty much any other strip hotel, you can walk to your conference in 10 minutes or less, and you can complete the entire walk underground. Tons of food, cafes, etc. along the walk. Entertainment venues everywhere (obviously, it's Vegas).
SF/Moscone is the absolute worst for getting around. The other cities are ok-ish but only if you're staying at the hotel where the conference is being held.