My wife and I are planning a trip to NV, UT and CA in late May / early June. "Plan A" is to fly in and out of San Fran (mainly so that I can redeem a lot of BA Miles that I accrued in those far off days when I was a hardworking international jet-setter (!)). We would spend 2 or 3 days in San Fran and then fly to Vegas, have a day there and then drive to (for example) Grand Canyon via Hoover Dam - Monument Valley - Lake Powell - Bryce Canyon - Zion NP - Vegas - Death Valley - Mammoth Lakes - Yosemite and back to SF. Is end May / early June the right time to do this. i.e. will Death Valley be not too hot? Will Tioga pass be open? I hadn't really thought about it until I read some of the messages in this forum but would there be any advantage, weatherwise, in delaying the trip until autumn? (sorry, fall - forgive me, I'm a Brit!)