Initally met 1 on 1 at my college and was contacted for a second interview to take place at their headquarters in Tucson AZ. They put us up at the Westin and the two day event consisted of a social hour and presentation on the evening of the first day. The second day consisted of touring the campus and several interviews which were 2 on 1. Situation was very competitive as they fly out a couple hundred candidates at a time and do this event bi-monthly I believe. Focus on technical experience vs personality, it is an engineering firm after all.