Staves have caster stats such as +Int, Spi, Stam, spell dmg and healing and the like.
Maces can have stats for a mix of casters and melees, such as Int, Stam, Str, +dmg & healing as well.(usually for Druids, Shammies, and Pallies)
Axes you'll notice will have more pure melee stats; AP, Str, Agi, Stam.
So consider the bonus stats when you want to use something to melee with!
Edit: In my experiences so far, I find the mob is burned down much faster dual wielding, and while dual wielding I find flurry to be up more often as well.
Having a good two hander has good burst damage, which is good for PvP. It just hurts when you miss wielding a big bad two hander, because you have to wait longer for that next swing, which can slow things down a bit. When you get that triple crit WF proc though, it's so sweet.
Edited, Oct 15th 2007 11:59pm by Zornov