Mike Keitz suggested placing the pull-up directly on the switch,
rather than at the PIC, which is sound advice ...

  except ...

that my first thought when I read the original request is that "this is
what the Port B weak pull-ups of various PICs are for".  Presuming that
parts count is a prime consideration, it makes sense to use these where
they are provided.  The voltage divider effect is of concern but the
maximum specified value for the weak pull-ups is 400ľA corresponding to
the logic low maximum specification of 800mV if a 2K resistor is used in
series with the pushbutton.

  At worst, the 2K resistor will draw 2.5mA at 5V from a port output,
well within its drive capacity for as long as it needs to be asserted to
send data to the LCD.

  In this case of course, the I/O pins should idle as LOW outputs or
inputs.  The weak pull-ups are disabled on pins while they are outputs.
Current flow through the switches while they are held closed is unlikely
to be a problem for pushbuttons, particularly if these steps are taken.

  Well, that's my theory anyway!
        Paul B.