OK, for short term, close-to-home missions and if you're not in a hurry.
For longer missions, I'm with Lee.
http://www.physics.montana.edu/faculty/cornish/lagrange.html
It's logical that asteroids will ultimately come to rest on the L-points of that highway:
http://seds.lpl.arizona.edu/nineplanets/nineplanets/asteroids.html#asclass
Marcia
