help me plan my road trip

[jawhoo]

As luck would have it, my roomate and I will both be quitting our jobs in the next 6 weeks, and neither of us is doing anything until late August. So, we're planning to take a month long road trip since we have all this free time, and drive from Washington DC to California and back. I'd like suggestions from anyone with things we should see or do during this trip.

So far, the tentative plan is to leave Saturday July 7th and return Sunday August 5th. We want to spend 4 days in LA/San Diego, 1 weekend in Las Vegas, and we'll be stopping for 3 days in Arkansas to see my family. What else?