Member Pipcard on this forum mentioned a proposal to the use the shuttle ET's as space stations on this thread, "
Secret plan to privatize shuttle; now, to a next-generation shuttle"
This is interesting because they would have two and a half times the habitable volume of the ISS. And if the SLS really will have a 95+ mT payload capacity to orbit, the ET could be launched to LEO on a single launch with extra payload available for converting the ET into a habitable living space.
I tried to get it also to the
Earth-Moon Lagrange points for the space stations NASA is considering but it is a bit too heavy while using propellant left over from the flight to LEO, instead of getting extra payload. However, I think it can be made to work if the shuttle ET was converted to common bulkhead design, to save weight.
Note that the ET's could also serve as quite large propellant depots at either location.