Looks pretty good. Here are some of my thoughts:

Big Sur is only about an hour from Carmel. I'm not sure it's worth spending a night at Carmel... there's not much to do there, unless you also intend to take in Monterey. Personally, I would stay a night or two in Monterey and then drive all the way to Cambria.

Las Vegas is only a 4.5 hr (in theory...) drive from LA. Depending on the price of flights, you could consider driving it instead of flying.

Also, what about Yosemite? May is the best month of the year for Yosemite and, if you haven't been before, it would be almost criminal not to go there! The waterfalls are at their peak in May and all the roads should be open (they close off a lot of them during Winter but the snow will have melted by May).

My final thought is why go to SF twice? You are going to fly into SF so why not just stay a few days there at first? You can always fly out of Vegas to go home.

If you did decide to take in Yosemite, I would fly into SF, then drive to Yosemite, then to LA, then on to Vegas. Yes, that would mean skipping PCH (Pacific Coast Highway) but, if it comes down to seeing PCH or Yosemite, there is no contest. Has to be Yosemite. You COULD take in both but Yosemite is a bit out of the way (or PCH is out of the way, depending which way you look at it). That would be a lot of driving.

i also cannot see the sense,in going back to SF,it just doesn't make sense.
i would definately,stay in SF,at the beginning & fly home,from your final destination.
i also agree,there is no way,i would do that itinary & miss out yosemite.
this is just my opinion,hope you enjoy your planning
tracy

I agree with Grey.......definitely try to get a trip to Yosemite in there, it's an awesome place and May indeed is a great time to go, that's when I went there and the waterfalls were spectacular. However, there was also a lot of snow around still and every single entrance to Yosemite except for the main entrance on the west side was closed! It was rather bizarre leaving Vegas and it's 104 degrees and driving up the east side of Yosemite in a blizzard!! I have video of me outside the car in shorts and t-shirt in the snow!

TC