I just came from 3 days at Kirkwood, CA. Would highly recommend it for advanced skiing/boarding. Though they had a heat wave this past week, there was a deeeep snowpack and if seasonable temps return, the whole Tahoe region, esp higher based ski areas, should be great around Apr 1. Mammoth or Squaw could also be good choices, they're even bigger than Kirk.
Alta/Bird are pretty renowned for the best late snow in Utah, usually a little dryer than Cali, again lots to offer for advanced skiers. No boarding allowed at Alta.