If you're traveling by air, make your reservations and get your seat assignments as early as you can. Requesting a bulkhead seat can give your more room to maneuver. Some spouses book plane seats away from each other, which lets one rest while the other minds the baby.
It's also good to stick to your baby's regular routine before you leave. Don't deprive him of sleep hoping he'll snooze through the trip -- it doesn't usually work.
For car trips, make sure you're clear about your route. You'll likely have enough distractions without wrestling with road maps. Draw up a trip timeline so that you have an idea of where you'll be when.