Green open space is addressed as an important urban planning strategy to ameliorate the negative environmental impacts of high density. The article presents a comparative study of green open space development models and associated use behaviors between Hong Kong and Singapore. The two cities represent two distinct models: “Concrete Jungle” where green open spaces are separated from built-up areas and “Garden City” where green open spaces are integrated in buildings. The research argues that the two distinct urban development models are shaping two types of use behaviors. The detached green open space in Hong Kong engendered active visits with high intentions and sensations; the integrated green open spaces in Singapore, on the other hand, caused passive visits with low intentions and sensations. This research draws attention to the overwhelming greenery in urban development that might attenuate the therapeutic function for healing and restoration. The spatial arrangement of green space distribution should encourage people’s intentions and aspirations for an active visit with social or physical activities. The planning and design of open space should also optimize microclimate conditions (such as shading, cross-ventilation and thermal comfort) to facilitate longer stays.