This report presents a study that investigated potential travel behavior changes in light of automated, connected, electric, and shared-use vehicle (ACES) technologies. Three main aspects of choice behavior were investigated: AV adoption and willingness to pay (WTP), shared mobility adoption, and mode choice. Particularly, this study focuses on exploring the roles of attitudes in individuals' travel choice behavior. Data collected through a stated preference (SP) survey were used for this study. The survey included a series of attitude-related questions that cover various aspects of user attitudes, which include general mobility preferences, perceived benefits and concerns of shared mobility, reasons against or for private ownership, and motivations for and desired features of AVs. Various modeling techniques were employed to identify influential factors and examine the impacts of attitudes, including error component models, structural equations model, and support vector machine method. The models identified various attitudes that played significant roles in individuals' choice behavior. These include joy of driving, technology-savviness, choice reasoning, trust issues, data privacy concerns, favor for private-vehicle utility, on-demand services, green travel preferences, and desire for efficiency and technology, etc. Model results showed that attitudes played important roles in shaping travelers' choice behavior. Incorporating these factors improved the model performance and prediction accuracy of travel behavior models, which will lead to a more reliable assessment of the likelihood and magnitude of behavioral shifts toward future mobility options. This study provides useful and meaningful insights into users' attitudes and perceptions toward ACES technologies and how these attitudes and other contributing factors may influence travelers' choice behavior. Recognizing that the market will not react homogeneously toward new technologies, the study results contribute to a better understanding of user acceptance and adoption of emerging mobility options and better assessment of their potential impacts. The findings could be helpful for planners and service providers to better plan for and address the needs and concerns of travelers.