IMHO, the Disney contract code gives the best discount.
I think the Disney coupons also give the best discounts too, but I just can't use them because of when my trip is. So far they all expire September 30 except for Disney coupon #10005317 which expires 4/1/02 and is one day free. That one isn't as good as the $20 one I have from Mileage Plus.
You can plug in each coupon with the Disney Club contract # and see which comes up the best, that's what I did. For me, my BJ's Club coupon was better than the Entertainment coupon. They are all around the same discount, between $10 and $20 off.
As far as I know, you can only use one coupon and also one contract number.