Mammoth was my first thought purely from a terrain open standpoint. Have friends planning to meet up there in late May/early June.
Did a ski safari in early May 2018 that started in Oregon and ended with a morning at Squaw and three days at Mammoth. Pretty good skiing 7:30am-noon at Mammoth. My ski buddy and I were using the MCP so stopping at Squaw it didn't matter that we'd only get in a few hours on snow. He'd never skied anywhere around Tahoe.
He went on to ski A-Basin before heading home to NM after dropping me off for my return flight from Las Vegas. Since he lives at 5000 ft, the high altitude doesn't bother him.
Check and see which lifts are open at Snowbird. I think the tram is offline for maintenance in May.