Yes, the 5.6V is measured with no load.
To measure the loaded battery, I leave the circuit built, but measure across the +/- rails of the breadboard? That measurement is about 3V... and sinking constantly. is that the issue??? I feel dumb. Plugging that back in...
Vo = (VsR2)/(R1+R2) = (3270)/(270+270) = 810/540 = 1.5V.
Measured: 1.3V for Vo, then back to the battery for a re-measure of 2.6V.
Thank you, James! I'll go find a healthy 9V for the remainder of my experiments. 
EDIT: Thanks, retrolefty, I'll switch them to 10k. How do I determine the right resistors to use for a given power source?