At DLP, unlike at WDW, the AP discount, when it is offered, is 25% of the room only rate. It's still better, but the discounts don't go as deep as they do at WDW where 40% off is not unusual.
On my last trip, I got the AP discount for the Sequoia lodge, during off season, and it was quite inexpensive. I can't break it down exactly by night right now, because weekends were a bit more, and I can't remember exactly how much we paid for our 5 night stay, but I remember it being "near" 80 Euros per night.
The New York and
Disneyland Hotels never have AP discounts. And beware asking for a room only rate - we stayed 2 nights in the Disneyland and I ended up buying a package, even though we had AP's, simply the package being offered at the time was actually CHEAPER than room only! NO logic in it, I know.. but that's the way it is at DLP, so be sure to inquire about both package and room only if you do purchase AP's.
Also, keep in mind you must have the AP to make a room only reservation or to get the 25% discount. The number is required when you make your reservation.
Even if you don't get a deep discount on the room, if you will be there for more than a couple of days, AP's are worth the cost - discounts on food and merchandise alone paid for ours over the 15 days we spent in DLP over a 365 day period.
If you have any more questions, just ask - we have experience with AP's at WDW and DLP so we are up on the differences and similarities.