Totally depends on your playing habits.
For a while, it was totally worth having a full set of four Wii controllers for me because we had a lot of parties at our place. After my wife finished school, we moved away, got new jobs, had kids, etc etc... it became much less useful since we don't have the same playing habits at all. I still want two full sets of controllers, but anything more is unnecessary.
However, the gold nunchuck is pretty sweet. It's the most useful physical reward from Club Nintendo so far, although I would argue that game downloads are possibly better. If you don't like the nunchuck then you can probably sell as a collector's item and get reasonable value for your coins (maybe buying a normal nunchuck with cash left over). If you have that many coins just lying around the question really does become: what else are you planning on using them for?