Hi Barry,
It feels like not long ago when I asked the same sort of question!
I can give you some pointers but the short answer is, your still gonna use alot of core hours.
So adjustable run time uses courant number to adjust the timestep a good artical was actually posted on the simscale blog:
So this can be taken two ways we can use it to ensure that time steps are kept at the correct length, but we can also say that if the mesh size is smaller the time steps will also be smaller. So a quick way to increase time step length correctly would be to only use the maximum refinment level that will represent your geometry correctly. Anything finer you will need to take the computing cost hit as a consequence.
the second peice of advice also relates to mesh size in a way. reducing the mesh size in terms of cell number to the point that you can run on fewer cores. This might seem counter intuitive, but the advantage of increasing cores is only a real time advantage, in terms of results per core hour there is a disadvantage due to comunication time between the processors. There is alot of information available online about this.
After these two there really isnt much more you can do, and you might just be better off asking yourself do I need transient results?
Hope this helps,
Darren