[ryanfreeborn]

Back when my friends and I played Catan a lot, we developed a simple way to avoid the spoiler effect: running point totals. Games are still played in regular fashion, but your victory points for each session are added up over time. Winning a game gave you an extra VP in the running totals. You can set the constraints to whatever you want: a year's time, 6 months, 10 games, whatever it may be...at the end of the time frame, whoever has the most victory points wins. Put some money down at the beginning, and you've got great sustained competition.

Obviously it only works if you play with the same people regularly, but in my experience that's actually the norm.