Your destination is within 1500 and time is okay- fly or drive?
I have actually driven across the United States by myself three or four times. And when I was a kid, my parents would drive from Missouri to Delaware every summer. So I'm going to have to answer...drive.
As a kid, I would deck out the backseat of the car with blankets, pillows, books, cassette tapes (Yes, I'm dating myself), notebook and pens. It would take about two days to drive straight through to Delaware, through the Appalachian Mountains. It definitely fueled my imagination.
To this day, some of the best sleep I've ever had was sleeping the car with the window down, wrapped up in a blanket and wind washing over me. That's one reason I now have to have a fan on me when I sleep.
As an adult, I've moved many times across the country, first living on the east coast and now on the west coast. I've driven the northern route, across Colorado, as well as the southern through the Texas panhandle and even along the boarder in El Paso. This is a beautiful country with amazing places to see and explore.
Besides, I'm not a fan of heights and although I have (and will if necessary) flown, flying still makes me a little nervous.