Nr, The valley route has more chance of delaying you because of weather but is nice if it's clear.
The other item to watch for is winds from the north if you're heading towards Las Vegas. As you approach the mountains that encircle LA to the north (and especially in the Cajon pass)the turbulence can be severe. I fly a 7500lb twin and have been tossed around like a rag doll in those winds. The notam-pilot reports many times have no mention of the turbulence in the pass at all. If even ten knots is coming out of the north I would be very dubious in a light, teetering head machine. If you do happen upon it you may be able to climb above 9-11,000 feet to reduce the turbulence.
Lots of traffic, watch out for that too !!
Enjoy the trip !!
T.