I took a trip to Las Vegas from Chicago. The train was late getting into Kingman, but there were two vans waiting to take passengers to LasVegas. The vans stop for a 15 minute rest break about half way to LasVegas. Getting a cab at the airport in LasVegas was no problem at all.
On the return trip, meeting up with the van at the airport to go back to Kingman, it's in a lower level area and the place the van meets you is not well marked. However, there's a police officer riding a bike and he'll tell you where to wait. I was really early getting there, so the van wasn't there yet. When the van did arrive, he parked there and put a sign on the top of the van that says "Amtrak". Also, if you are taking a cab to the airport, the cab driver more than likely knows where the van is. My brother-in-law drove me and he was clueless.
Unless it has improved since last October, the waiting area in Kingman to catch the train home is a sight to behold. It's in a very old storefront about a half a block from the tracks. There's a tin ceiling and a bathroom from the 1940's. The train crew is in the storefront next to the passengers and they'll come in and tell you when the train is arriving.