Where do you bike? Urban? Suburban? Will you park where lots of people pass by, or an isolated place? I think these factors have a lot to do with your choice of lock.

I live in a smallish town (but bike theft is common). I use a 5 foot cable most of the time, which allows me to lock frame, helmet and both wheels to light/telephone poles and such. That's a necessity, because I've found those to be the only options many times.

This is my lock:

http://absupply.net/detail.aspx?ID=1...rity-Key-Cable

It's good for here, but it probably wouldn't last 5 minutes in NYC. Beefy bolt cutter --> snip, snip --> end of story.