One of the reasons you want to interview people in three different places is that candidates will usually be at their very best in the first interview (likely in your office). After that, if they are pretending, the veneer will come off in subsequent meetings in out-of-the office locations.
Also, because most employees can only be successful in their jobs in different locations as well, it makes sense to witness your candidates in different settings. So, consider interviewing the candidate over a lunch at a nearby restaurant.
And, finally, consider interviewing them in a group setting where you invite a variety of your employees to be part of the group. If you do this, be sure to let each employee voice their “vote” regarding the candidate after the meeting.
There are lots more great tips like this one in Thompson’s and Tracy’s book, Now…Build a Great Business!