|  Commoning Vcc, Gnd, !MClr, RB.6 and RB.7 between the 3 F84's when
|plugged in, with 1k pull-ups on RB.6 and .7 for I2C, is the plan here.
|Don't think I want to try to program all 3 F84's in parallel, so
|unplugging instead of ICSP is a good idea here <G>

If you seperate the RB6 wires if the three chips, you can parallel /MClr,
RB7, VDD and Vss and still be able to ICSP them one at a time.  Given that
this would allow you to avoid the hassles of socketing (and allow you to
use a surface-mount part if desired) this could be a significant win.

Depending upon your programmer design, you may also be able to parallel
the RB6 pins but with, e.g., 470ohm resistors between each chip's RB6
and the I2C bus.  Your bus pull-up would have to be sized appropriately,
of course, but that shouldn't be a problem.  To program one chip, you
would ground out the RB6's of the other two.

Those sound like plausible notions?