I went on a different route. Vegas > LA > Santa Barbara > San Fran > Yosemite > Death Valley > Back to Vegas.
However, some advice. Based on personal experience, don't stay in Death Valley. Most places in and around the area are holes, and there really is *nothing* there (I know shock, but seriously, if you stop in a town near death valley, expect to be bored).
For Death Valley, aim to get their early on, spend the day there until the sun sets (as you get some amazing views), and then as soon as it'd down, put some miles behind you and get a long way towards Yosemite. You should be able to get far enough so you've not got far to go to get to Yosemite the next day.
For example - we stayed at the Amargosa Opera House which had fairly decent reviews. Man it was terrible. No food after 8pm, and nothing nearby to eat. We had to drive miles to find a casino which still served food. The bedrooms were rotten, and the included "continental breakfast" was a pre-packed mini muffin and some tap water!
Aim for about 2 to 3 days in Yosemite - but book accommodation. If you go peak season then all of the half decent places will disappear fast. I know this removes some of the 'freedom', but there are some really dodgy places that call themselves 'hotels'.
I'd aim to spend at least 2 days, ideally 3, in San Fran. We stayed at the Parc 55 hotel. It's really central, quite reasonably priced, and very plush. Definitely check it out, I highly recommend it. We "biked the bridge" which was pretty good - you get bikes for the day and can see most of San Fran that way. Bike across the bridge and then get the ferry back. Obviously there's the Rock, which is also worth seeing. You should easily be able to fill a few days there, and there's pleanty of nightlife near your hotel.
Erm, other tips? We were doing a lot of driving and tending to spend a whole day in a place and then get to the next destination fairly late on. The problem with this is that everywhere in America seems to stop serving food at 9:30/10pm. It's really odd. Even in Vegas we couldn't find anywhere other than a Maccy Ds to eat after 10. It's not so bad if you're staying at a decent hotel who will have room service, but if you're in a smaller town, make sure you get there at a decent time if you want a proper meal.
Enjoy mate, I hope you can make sense of the waffle!