I don't have the patience to wait too long, so i broke with loyalty and got the Simpsons minifigure series from Wal-Mart this past weekend.
This is my best performance yet, having gotten all sixteen by purchasing just seventeen figures (anybody need/want a Lisa Simpson?) and only taking about fifty minutes (in-store time between the two visits) to find them all.
It turns out they were surprisingly easy to figure out. The Ralph Wiggum vs Milhouse Van Houten (sp?) distinction was tough, but the rest were actually really easy to distinguish. Lots of new accessories this time around. Loads of fund, too.