When I first looked at the giants polymorphing rules, I thought: woa, lots o' rules. Then I looked harder and went: wow, it just does what I thought it did in the first place, with maybe one exception (sp?) (which he pointed out in his examples). I liked the options for various polymorphng spells he presented. My only complaint was the template usage, IMO it would have been simpler just to say that any form of shapechanging/size changning cancels the last one.
Now, TheThan's stuff:
Sounds good to me, I'm inclined to fight for more polymorph options, but you really don't need many, and I'm soft for the arcane anyway.