I'm learning a lot in the last 24 hours. The dealership just called and confirmed what the independent shop told me: after replacing the valve cover gaskets and the lower oil pan gasket, now it's the upper timing cover ($2500). Where it get's scary is what could happen but hasn't yet. If the lower timing cover goes, that's $7500 and basically forces them to redo both the upper timing and valve covers again (where I spent the first $50000.
The good news is that the place that has worked on it already seems willing to give me a severely discounted rate.
I'm ready to trade this sucker for a Ford Focus or a Prius!
Thanks to all of you for your help.