A few sugesstions...

1) Sign up for a month's worth of unlimited gprs and get an inverter to power your laptop. Being able to surf (no matter how slowly... you can look out the window while pages load) really makes being a passenger go faster.

2) Full Size Spare - If it'll fit, it'll save you so much hassle should you get a flat.

3) Consider a bra for your vehicle. While they're hideous to look at, you're going to be doing so much driving in such a short time period it may be worth it.

4) Read about where you'll be. Remember books are free at a bookstore as long as you read them there while enjoying an overpriced beverage.

Matthew