Traffic in CA is TERRIBLE but it's worth it. Also, keep in mind that if you have a towed you are pulling the speed limit is 55 on all roads so you can't be running the 70 MPH speed limit on most of the Interstates.
As you come down the 15 into the LA area you will want to take 215 and reconnect with 15 on the other side. There is little mileage difference but you have a better chance of not being stuck in traffic.
Now, out of Phoenix heading for Vegas you are going to want to take 60 (60/93) through Wickenburg to 40 and then 93 into Vegas and by the Hoover Dam. The new bridge does not give you any views of the Dam so if you want to you can divert and drive across the dam or stop on the NV side of the dam and take your car down for a look see.
