Take the slow, scenic route if you have time. Ktspktsp and I just gunned across the country from PA (technically DC, I guess) to WA on I-90, and most of it was boring as hell. We got to meet The_Jazz, though, which was fun
and the natural sights were the things really worth stopping for... unfortunately, they did not happen until we were already nearly across the country. If we had had more time to enjoy ourselves, we would definitely have taken a more meandering route and checked things out.
Will you be hauling crap in your car? We shipped 19 boxes to make life easier, but the car was still full... would have been nice to have the back seat empty, in retrospect, so that's another factor for you. Will you be camping or moteling along the way? Do you have A/C?