Best time of year to visit LA/SF/Yosemite/Death Valley/LV/GC/LA??

One thing to consider is the length of daylight hours at those times. May has much longer days than October. Death Valley is awesome but will be very hot at both times and Las Vegas will be very warm also. Can't help you with Tioga, but if you head into the mountains it will be cooler and you may have snow at either time. There was still snow at Cedar Breaks when we were there the last week of May this year. This might also happen in the high areas in Sept/Oct.

Sounds like a nice trip. enjoy!

I think if you check these 2 web pages that give Tioga pass opening and closing dates, and Death Valley weather, you will conclude that September/October is a good choice.

http://www.monobasinresearch.org/data/tiogapass.htm

http://www.weatherbase.com/weather/weather.php3?s=746191&refer=

Of course Death Valley will be hot/warm. It's supposed to be!

If Tioga Pass is closed, the quickest way to Death Valley is to go out fo SR 99, south Bakersfield, across to US 14 on SR 58 then north on US 14 to SR 178 through Ridgecrest, Trona and the PanamintValley where you'll cath SR 190 into DVNP. Alternative, stay on 14 as it joints 395 north of 178 and turn onto SR 190 in Olancha. To Furnace Creek figure 3 hours for Yosemite Valley to Bakersfield and about 4 hours from Bakersfield to Furnace Creek.
Personally I prefer early May to Septeber, wildflowers often still in bloom then.

Hmmm, tough choice isn't it. Have to say the longer days of May are appealing...
We live in Queensland, Australia so the heat shouldn't bother us too much. And like you say - it's supposed to be hot in Death Valley!
Thanks for the route info boom-boom - will look that up. Wildflowers sound nice too.
Cheers,
J

It's pretty much just foreigners who go to Death Valley in summer (May thru October). If you just drive through and see the roadside attractions, you should be OK. But, most of the hiking and dune exploring in the Valley itself will be too uncomfortable because of the heat. Death Valley is a winter park, best from November through April.

A good time to visit Yosemite and the Grand Canyon is late May and early June. Usually they try to open Tioga by the last weekend in May (Memorial Day) but in years of really heavy snowfall, this may not be possible. Both Yosemite and the Grand Canyon are fabulous at this time of year. You might consider also visiting Zion and Bryce Canyons since you will be in the neighborhood and these are also best in late May and early June. Since you will be traveling by RV, the longer days of Spring will give you a lot more hours for enjoying the parks as others have said.

For LA and SF, anytime is pretty good. But, for the coast September and October will most likely have better weather than May and June. The coast is often at its warmest in October.