We took a full month. Dh wasn't able to get a full month off work, so he just did the driving across and back with us...our schedule was like this
Day 1: Drive from Nothern VA to the smoky mountain, Tn
Day 2: Smoky mountains
Day 3: Depart Smoky Mountains, drive towards Arkansas, stop at Blanchard Springs Caverns in Ozark national Forest for a tour of the Caverns, stay overnight in Little Rock, AR
Day 4: Drive to Oklahoma City. We did stop at a Route 66 museum we saw on the way, but that was an unplanned stop. Overnight in OKC
Day 5: Drive through the TX pan handle and to Santa Fe, New Mexico. Overnight in Santa Fe
Day 6: In the morning visit Loretto Chapel in Santa Fe, Afternoon visit Petroglyph National Monument in Albequerque. Evening drive to Roswell. Didn't arrive in Roswell 'till around 9 pm or so? Overnight in Roswell
Day 7: Morning visit to the UFO museum in Roswell. After lunch drove to White Sands National Monument. Slid down the Sand dunes (able to rent sleds at the visitors center!). Got some dinner (wasn't too much in the area, I think we ended up at Applebee's?) then back to enjoy the Sand Dunes at night (open 'till about 9 pm during the summer, I think?) Spent night in Las Cruces, NM (didn't arrive at our hotel 'till late!)
Day 8 Drove to Tucson AZ, visited Saguaro national Park. Spent night in Tucson.
Day 9 spent a little bit more time in Saguaro Nationa Park (from what I remember, it was kind of split in 2 different sides?) then drove to San Diego. I think we arrived in San Diego around 5 pm or so.
We spent one day in San Diego (
Legoland) and then Dh flew home to VA. Kids and I stayed in San Diego with family for a week
Next week kids and I went to Sequoia national Park (2 days), Yosemite National Park (2 days) and then a couple days in Orange County.
Dh flew in to meet us again (plane arrived late at night in San Diego) and we spent that night in a hotel in Riverside, CA.
Can't remember what day I'm at now so I'll start over at 1
Day 1: Drove out to Las Vegas area. Visited Hoover Dam and took Dam tour. Spent night in las Vegas since there isn't that much else around there. We didn't do a lot of Las Vegas since we had small kids but we did go down to the Bellagio to see the water fountain show when it was still fairly early at night. Had Crepes for dinner at Paris...
Day 2: Drove to Bryce Canyon. Spent day visiting Bryce Canyon. Spent night in hotel nearby (can't remember the name of the city)
Day 3: drove towards Salt lake City, stopping at Cedar Breaks along the way. Arrived in Salt lake city late afternoon/early evening. Drove by the Great Salt Lake and let the kids go in for a quick swim, but honestly it was kind of gross water . It was mostly just so they could say they've done it....
Day 4: Drove to Wyoming. Stopped at Fossil Butte National Monument. Spent night in Cheyenne
Day 5: Drove to Mt. Rushmore. Visited Mt. Rushmore and saw laser show at Crazy Horse. Arrived in Hotel in Cedar Rapids VERY late at night (midnight?)
Day 6: Whole day of driving. I think we left around 9 am. Drove rest of the way through South Dakota (stopped at Corn Palace), through MN and into Wisconsin. Arrived at hotel in Madison close to midnight.
Day 7: Drove to Chicago and visited with my brother there and his wife
Day 8: Chicago with brother and wife
Day 9: Drove from Chicago to Lexington KY. No planned stops but along the way saw signs for Fair Oaks Dairy adventure in Indiana and ended up spending several hours there.

Spent night in Lexington KY
Day 10: Drove home to Nothern VA!