So a few responses/questions to/from the above:

*Yes, the bike will be indoors at night, rarely locked outdoors during the day, and never locked outside for extended periods of time. My place of business even has a secure, indoor area for storing bikes during the work day. Theft of the seat isn't my concern - just comfort and durability.

Thank you for all of the suggestions on tail lights. You've given me three or so highly-rated (on amazon) models for me to run by the folks at my LBS, which I truly appreciate.

Two new questions:
--Rechargeable seems to be the "in" thing, but I'm wondering if it isn't better to get one that takes standard batteries so that more could be bought on the road if necessary (if, for example, I forget to charge!) Any thoughts?

--I would love some recommendations for headlights as well, if anyone has any strong opinions.

Thank you all again!