Indicators are a fundamental tool for destinations in their progress towards a more sustainable tourism development. However, the lack of real progress and the accelerated technological change are obliging policy makers to rethink the existing indicator systems. This paper examines the relationship between smart cities and destinations and sustainable tourism indicators by analyzing proposals at different scales. It provides a critical review of international smart city standards and the role that sustainability indicators play within them. Then, it conducts a content analysis of planning instruments applied in smart strategies in Spain, focusing on how sustainability indicators are considered under the smart paradigm. At the regional-local scale, this research compares two sets of indicators and tests the scientific validity of one of them for addressing the imbalance suffered by many indicators between their usefulness for policy makers and their academic rigor. The results show that little progress has been achieved despite the appropriation of the sustainability discourse by smart city and smart destination promoters. These findings reveal the (limited) real contribution made by smart cities/destinations to sustainable tourism development and contribute to identifying weaknesses and opportunities so as to redirect smart policies and projects. A final discussion contextualizes the findings within the novel framework of smart sustainability and highlights the need to reinforce public governance of urban and tourist spaces.