How do evacuees behave and what factors influence their egress selection behavior of stairs or an elevator during a high-rise building evacuation? These issues remain unclear given a paucity of research. In this paper, a series of experiments and questionnaires with 45 participants were carried out to examine the effects of non-irritant smoke and participants' knowledge of evacuation procedures (especially elevator evacuation). After each experiment, participants were asked to respond to a questionnaire. The results of evacuation times for the elevator versus stairs, the proportion of elevator users, elevator wait times, and redirect behaviors are analyzed and discussed. In experiment 1, 26.7% of 45 participants chose the elevator. In experiment 2, non-irritant smoke was released, and the proportion of participants who used the elevator decreased to 24.4% of 45 participants. Before experiment 3, we shared information about the evacuation (i.e., an explanation of evacuation procedures and elevator evacuation experience) with the participants, after which elevator use increased to 40% of 45 participants. As a result, we found that non-irritant smoke and knowledge of evacuations affected evacuees' behavior; however, the gap between the proportions of participants who reportedly preferred to use the elevator and who actually used the elevator was large. According to the questionnaire, the proportion of participants who wanted to use the elevator was 55.6%. Moreover, elevator overload, physical fatigue, and social bonds were observed in our experiments. In conclusion, several suggestions are given to building designers, and basic data (such as evacuation times and proportion of stairs or elevator use) offer insight for building safety engineers in designing evacuation strategies incorporating stairs and elevators.