A thought that occurred to me is that while aiming for Mars is a good objective, there are other practical goals to be achieved by further Moon trips.
The establishment of a permanent presence on the Moon would be a good test bed developing technologies for living and working in a hostile environment. The specific ideas I had were, permanent habitat, is it better practically and economically to construct a domed enclosure above ground or tunneling into the ground, either way you need to supply Oxygen since living in suits long term is not doable, underground facilities, depending on seismic conditions would be less likely to develop leaks.
Another technology that could be explored is adapting the soil to agricultural use since shipping food over such distances would also be impractical due to time and expense.