You can add a [@target] to all your spells. This stops your spells from automatically targeting a mob to cast, they just wont cast if you have no target.

/cast [@target] spellname

It does give you complete control over your targeting. I pretty much added that to every spell in every macro for every class. I got tired of finishing a group and if I accidentally hit the dps key one too many times they would pull the next group.