The 8 bay's advantage over a 4 bay, is most prevelent when the two sections are at angles between 60 and 300 degrees from each other.  I would aim the one antenna North East, and the other one, South.  The North East one will pick up Toronto, the South facing will pick up Hamilton, Buffalo, etc.  Make sure you can get at the antennas, to fine tune their directions.  making sure that you maintain a close to 90 degree angle.

You can also use an amplifier that takes multiple inputs, these contain circuits that will fliter the signal so that the strongest signal gets through, and the slightly weaker one gets filtered out.  I believe that some of the Channel Master amplifiers have this.

The other issue, the higher the antenna, and the more open the antenna is to the outside the better.  An antenna in a basement room needs to be aimed exactly at the signal source and needs to be fairly close to the source.  An antenna that is outside, 1m off the ground will pick up much more, one that is 3m or more off the ground, will pick up much more.  Some people on high floors of apartment buildings with the balcony facing the right way, can get incredibly distant signals, off the balcony.