Isn't the 2 nights free offer about 50% off as you are getting 4 nights for price of 2 (so paying half). Having said all that, Disney make the prices up as they go along as quite a few on here have noted supposed RRP prices which seem to change when an offer comes along?

Someone said it might be to do with summer/winter price setting?
I think we are going to wait (someone here said the nights free offer ended in August, as it's 28th June (thanks for that!) I'm a little happier to wait until after then and see what happens I guess). We can only stay for 3 nights so while it is a good deal (33% off as one night free), it's not the best.
I'm hoping for our dates we'll get a flash sale deal - will be a first though as never managed before!!
If not, then we have APs and I'm hoping that they will have a 35% off AP rate so it will work out about the same as the one night free anyway.
It's so hard knowing when to book. As others have said, normally you can upgrade especially if you have to pay more money but this isn't guaranteed. Some have had issues with trying to upgrade and haven't managed it, but on the whole, most have. So it's a guessing game!