I did my Instrument training in nearby Ellensburg, WA, and shot a lot of approaches into Moses Lake. We'd occasionally see Boeing test flights, but, more frequently, we'd be sharing "the pattern" with Japan Airlines 747s - JAL did a lot of training there (more than 10,000 crew members). That was where I had my first, and, thankfully, my worst encounter with wake turbulence ...!
JAL trained at Grant Co. until late 2008 - the story I've heard says that they're downsizing their 747 fleet in favor of 787s, so they don't need the larger runways, etc. That was the end of an era - JAL had been there for 40 years, and, for 30 of those years, they had a program where they'd give every 6th grade student in the city a free 747 ride ...