Are you camping? If so good luck getting camp grounds in route or hotels for that matter. I did a road trip from here in VA over the span of about 16 days and here was our itinerary:

Mount Rushmore/Crazy Horse -arrived day 2 was pretty cool
Yellowstone-stayed 3 nights and would have done more
Yosemite-2 nights
Sequoia national park-2 nights (i think) probably my favorite spot..crazy road getting into the park and saw two bears and countless other species
Santa Rosa CA-2 nights
Grand Canyon-2 nights

We then headed back to VA.

It was a great trip and the two spots that i think were cool but i wouldn't go back are Mount Rushmore, i would go just to see it on a pass through and keep driving for the day, and the Grand Canyon. If i went back to the grand canyon i would definitely go to the North Rim again and do more back country hiking.

We learned quite a few things though. One, don't bother bringing groceries other than drinks and snacks. Just stop along the way at grocery stores. If you are camping, you can generally call one park and make reservations at pretty much every national park at the same time. Get the annual park pass as you will save some money most likely. Plan your route to go through some nice scenery as well. We chose to drive through the Tetons on our way to Yosemite i believe.

Also, unless you have a short day drive planned never arrive and leave the next day. It will not allow you time to see what you want and just tire you out. We stayed 2 nights or more pretty much everywhere. If you are camping, stay in a hotel every 3 or 4 nights as it will be a nice change but i do have to say, the majority of he campgrounds we stayed at were really nice and had great facilities. Use a GPS but don't completely trust it and verify with some maps just to be safe.

I put all of our places we wanted to see in a spreadsheet that i had columns for miles between, cost of park, nights in park, estimated fuel cost and whatever i wanted to see in each park which definitely helped out and my cost estimate was pretty much dead on and we travelled when gas prices were their highest in probably 20 years in july of 2008.

I will also say you are making a huge mistake by not hitting Yellowstone. I have been there a few times and i am amazed each time i go and am always looking forward to my next trip out there, no place in the US like it.

Oh and if you have been thinking about getting a new camera do it, and get the best you can afford. WE took tons of pictures which some turned out great enough to be framed and hung throughout our house

Have fun and enjoy the drive....