Best battery configuration
No - you've still got 8 AH of 12 volt batteries.

In fact, the second arrangement will last a much shorter shorter time, as the batteries on the right will be trying to charge the batteries on the left - if those are already fully charges, they'll just heat up and gas (and may be damaged).  The right batteries will be discharged to 12 volts or so, then no current will flow - you won't get any use out of the left batteries.