As has been said before here, I tend to play through Good first, then when I finish (or get stuck/bored which is more likely) I'll start a new game as Evil. One thing I've noticed though is that the effects of picking the Good options seem to take longer to manifest themselves than the Evil. For example, on Fable TLC I'd take ages being nice before I get my halo and butterflies, but I can grow horns and glowing red eyes before even leaving the Guild. I guess having an endless supply of innocent bystanders who don't actually want anything kinda helps in that department.
Also, on GalCiv2 the Evil options always seem to give you more benefits than is balanced by the other races' disapproval of you. I'll often end up taking the neutral option just so I can actually get some sort of beneft without everyone hating me.