Very good posting Dan.
We used to go through 1000-1500 gallons of fuel oil before my first OWB. At over 3 bucks/gallon, that's a minimum cost savings of 3k/year.
We also save $60-$80/month on hot water electricity costs for more than half the year.
I am at the age where I really need the little bit of extra exercise that processing firewood provides. It's very hard to put a price on what the exercise might be worth, but I factor it in as an added benefit and not an associated cost.
And like you Dan, processing firewood gives me a perfect excuse to get out of doing things that are unimportant to me(hanging out with in laws, participating in her snooty friends activities,etc.)
I'm on my 7th year with an OWB, and I feel the system has paid for itself at least two times already.
AND...I have a pretty cool chainsaw collection my bride isn't totally aware of yet