As digital cultural collections become increasingly sophisticated in their scope and functionality, there is a need to build an in-depth understanding concerning the information behaviors of users in this new domain. Research has demonstrated that many digital museum visitors are engaged in casual leisure during exploration of a collection, suggesting that they do not have an inherent information goal but rather seek new experiences or learning opportunities based on personal curiosity and moments of discovery. Consequently, understanding how to translate casual leisure contexts into meaningful interaction design may play a critical role in designing engaging digital collections. Our study reports on the user experience of a largely unexplored user interface design framework called rich-prospect, which was originally developed to enhance browsing and discovery for complex visual collections. We performed a mixed-method, within-subjects study (N=30) that simulated a casual leisure approach to information browsing and retrieval across three different rich-prospect interfaces for digital cultural heritage. Our results show that rich-prospect scores well in the hedonic facets of its user experience, whereas pragmatic aspects have room for improvement. Additionally, through our qualitative analysis of participant feedback, we derived salient themes relating to the exploratory browsing experience. We conclude with a series of design implications to better connect interactive elements with casual leisure contexts for digital cultural collections. © 2021 Owner/Author.