Generative Artificial Intelligence (GenAI) is becoming an integral part of travel planning. This fundamental transformation is changing the definition of travel decision delegation, calling for fresh research into responsible AI in tourism. Drawing on agency theory, trust theory and decision delegation framework, this study conceptualises five responsible AI characteristics (reliability, fairness, trustworthiness, accountability, transparency) as evaluative signals for travellers to assess GenAI across three decision delegation levels, i.e., attribute set, choice set, and final decision. Using a multi-method approach, we analyse data collected from 421 travellers. Findings suggest that reliability and accountability are consistent drivers of delegation across all levels, whereas trustworthiness is a threshold condition that becomes significant at the attribute level. We also found that excessive transparency can lead to cognitive overload and reduce willingness to GenAI decision delegation. Our findings encourage future research into responsible AI development in understanding system complexity, algorithmic explainability and traveller delegation confidence.