Modern planning techniques for distribution systems consider, in addition to the conventional grid reinforcement, the provision of power flexibility from local resources. This solution is demonstrated to be cost-effective in numerous cases. However, distribution resources might be required to provide services to transmission system too, and this aspect needs to be considered within the selection of the best distribution planning options. This paper investigates a distribution network planning strategy based on different trade-offs between “minimization of investment costs” and “maximization of distribution flexibility for transmission services”, which is aimed at supporting a cooperative (but decoupled) planning for both distribution and transmission systems.