This question is not just related to wifi of course.

My understanding is if the dipoles are opposite of each other
(example 1: -----O----- ) then the lobe is an equal donut
shape from the center. I would get equal focus upstairs
downstairs ends of the house if wifi base is placed in the center.
(a big vertical donut sitting in center of the house with edges
of donut touching roof, 1st floor, end to end in the house [ O ] -- house )
(nulled in the front and back of the house.

What does the lobe look like if the dipoles are vertically
opposite from each other? (Example 2: |_o_| )
Is the majority of the lobe pointing to the sky and less to
the ground? Wouldnt that take away strength from the ends
of the house? Or am I totally off base? This question comes
from a recommendation that the antennas should be vertical as
in example 2. Maybe that is the idea is to lower interference
to neighbors. Thanks for all your input... Dean

Dean,
Since anything around an antenna affects/distorts the radiation
pattern to some extent, and since a dipole's radiation pattern is
sort of directional (depending on a lot of things), the usual vertical
antenna, being 'omnidirectional' would mean that the distortion
probably won't mean a 'null' somewhere in the house. (Wonder if I
could make that sentence a little bit longer??) That 'donut' radiation
pattern is the 'ideal', not what actually happens in most cases.
(There's not really a hole in the middle either.) Which would be
'beter' in your situation? Beats me. You might try it ans see, but
have the vertical antenna just in case...
'Doc