My current plan is a stacked pack.  Turns out very similar to A123's set-up but without laser welding. :)

Originally I was planning on 3 packs with just 66 cells in series but a BMS makes that less then ideal so I think I will be doing 3 packs of 3P12S.  I am still working on the electical connection but am leaning toward a simple clamp and spacer system.