1. Most likely, when you bring candidates on campus it will be winter. If the interview is to include a campus tour by foot, have that on the day the candidate doesn't meet the dean, and arrange for that day to be more casual. Remember to tell the candidate this, so that he/she can wear more casual clothes. Think this doesn't matter? You try walking on ice in a straight skirt and two inch heels.
2. Be careful who you send to the airport to pick-up and drop-off the candidate. You might be tempted to pick the only person who is willing, but these are the candidate's first and last impressions of the department. For the pick-up person, you want someone who is easy to talk with, and will not say bizarre things about the department or harass or scare the candidate (yes! it does happen!). For the drop-off person, you want someone who might be willing to either answer last questions, hash over the interview, or leave the candidate to his/her peace. If you don't think you'll be able to pull this off with all the candidates, consider using a limo service. You can just budget this into the transportation costs. It works great.
3. It's nice to give candidates time to adapt to their surroundings in the morning, but if you are not taking them to breakfast, be sure to give them ideas of where they could go and a way to get there. (Often candidates stay on campus. At small schools there sometimes aren't nearby places to eat other than the cafeteria. Can they eat there? If so, tell them.) Some people don't eat breakfast, but for those of us who do, it's essential. Be sure to make it clear whether or not breakfast will be part of the schedule each day.
4. Try to be flexible in scheduling so that candidates are not forced to miss more of their teaching than they must. While it might be difficult to corral all of your faculty in on a certain day, just remember that every day of class the candidate misses is one more chip on each of his/her students' shoulders. Many candidates have several on campus interviews, and missing many classes makes for a difficult/horrible semester for even the most committed teachers.
5. Make sure to ask about the candidate's dietary restrictions, allergies, other special needs, etc. If you house an asthmatic person in a smoking hotel room, or feed a vegetarian at a meat-dishes-only restaurant, your candidate will have a very negative experience and may not accept a job offer.
6. Don't forget to put a little bit of flex time in the schedule, so that the candidate can go to the bathroom! It's also useful if candidates have a few minutes to themselves from time to time, in order to relax, recharge, jot down notes, etc.