Depends on the trip and how I'm getting there. I prefer to arrive the day before if it's an overnight flight through multiple time zones. For a short distance, one-day domestic business trip I arrive on the day of.

A related issue is the unwillingness of some employers to consider travel time as part of your work day. If I'm flying out at 6am for off-site meetings and my return flight lands at 11pm that's a 17 hour day not an 8 hour one although many bosses would disagree.