castsequence macros rock. I've used them extensively on my lock since I found out about them, and never looked back.

The direct damage castsequences are probably the easiest to macro up, but i think a little extra thought can yield ways of having multiple classes working together.

One thing - And bear in mind I'm not sure about this.

Your last couple of examples your mage is casting arcane missiles which is a channeled spell. If you were pressing the key for the next spell then I believe that it will stop the channeling and do the next spell, which may be a waste of mana on the mage if you dont wait for the channeling to finish (But then means your other chars wont be doing daamge while waiting).