Just been reading an interesting article on the DLPR blog about (their) summer increases in prices. If you are planning on a trip to the resort for more than a few days its seems better value to purchase an AP than a multi day ticket... particularly if you are not staying onsite.
eg: Dream Passport price AU$269.00 ( premium passport, no block outs, significant extras)
Fantasy Passport price AU$188.00 ( a few block out days and reduced discounts)
4 day/multi park pass ( adult) AU $244.00
why on earth would you buy a multi day ticket anymore?