I posted something about this earlier, but I think it got buried in a stale thread:
Ever tried a Club bass with the so-called 'cavern' pickup spacing? I'm thinking about picking one up sight-unseen (it's a custom shop order), but figured if you've ever laid hands on one then you'd be the guy to ask. This guy seems to get a nice milky/chunky tone with one:
http://www.youtube.com/watch?v=gW-it-PNc4A.