As for bench players, if you're in a standard 21 player/team league, the 5 bench spots are for hitters and pitchers combined. I would recommend that at most you use three of these for hitters. I don't have any hard numbers, but it seems easier to find competent hitting on the WW than it is to find reliable pitching. Hence its better IMHO to use bench spots for pitchers. The only time when I would load up on bench hitters is if you have a starter who is injury-prone or plays sporadically (Chipper Jones, Ken Griffey, etc).
I play mostly roto though so it might be a little different for H2H. Also I've noticed there's no "super-utility" player this year that's really worth owning in shallower leagues (ie someone with 3 position eligibilities like BJ Upton or Chone Figgins last year). Braun, Atkins, Swisher, and Berkman are really the only sluggers with multiple eligibility, which bumps them up a little in drafts.