I would definitely do airfare separately!
Get a really good Disney TA (not your local one) lots of great ones around including
Dreams Unlimited(sponsors the Dis boards), MEI/Mousefan, etc.
They will help you figure out the best deal FOR YOU. There are tons of different ones that pop up and just because it sounds cool...doesn't mean it will cost you less $$.
A good Disney TA will not only help you figure out the best deal for you...but will stay on top of new deals and reevaluate each time to make sure it continues to be the best option.
For example, we (me, dh, dd10, ds5) booked in August 2010 for our August 2011 trip. When we booked we did so w/
free dining. Since then deals have been coming out of the woodwork...35%, kids stay/play free, and we received TWO PIN codes... guess what, for US...free dining is still the best deal because dd will be turning 10yo a few weeks before our trip and will now be an "adult." If she was still a "kid" something else might have been better...but in our case, this is it...so far!
