Sore bottom keeping you from riding? Maybe it's time to replace that fifty-year-old piece of plastic that you're calling a saddle. Similar to how a comfortable pair of boots can make or break a ski trip, a comfortable saddle can really make a difference in a long-distance bike ride.
The gel saddles will bring immediate comfort, and are available in a few different sizes. If you've got a long-term investment in your ride, and a bit of class, you may want to invest in a Brooks leather saddle. True, it's going to take a few months to break in that leather, but man oh man, the payoff is totally worth it.