18650 pack! 3 – cell or 4 – cell? Which is best suited for 12v applications??

I am having a hard time getting my head around using 18650′s for a 12v application! If I put 3 cells in series at most I will get 12.6V and least 9V If I use every last mah in the pack! Now most of my gadgets refuse to work below 11V

So my problem is do I use 18650′s in a 3 cell pack and enlarge the pack in size and weight to achieve a larger capacity! Or do I compile a 4 cell pack with a higher voltage of 16.8v and utilize a god buck converter to bring the higher voltage down to a usable level and accept a loss of power in the stepping down process as heat?