Thanks for the input.  I have settled on a 1/2 AA size Lithium Thionyl
Chloride (Tadiran XTRA High Capacity) cell with the appropriate holder in
digikey.  This seems like a pretty PIC friendly solution.  3.6V with a very
pretty discharge curve (long steady voltage with a quick drop at the end of
the life) and rated capacity of 1200mAh designed for long-term low current
operation for 5.09 (10).  This should easily get me over a year of battery
life and the holder should fit my enclosure with room to change the battery
perfectly.

Nick

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