I think there are 4 keys when planning a trip with an AP.
1) Only one person needs the AP to get the AP room rate. The added cost of the AP over whatever ticket you would normally buy can be paid for in just a night or two of an AP room discount.
2) Reserve a room you can afford and are happy with before the AP rates come out and then either upgrade when the AP rate makes it cheaper for an upgraded room or just take the extra $$ off the rate you already have. A simple call to CRO will get it done.
3) You don't have to have the AP when you make the ressie. You just have to prove you have one when you check in. If you buy the AP in advance you'll get a voucher to convert to the actual AP at one of the theme parks. This voucher will be ok at checkin, sometimes they make you return with the actual AP, sometimes not.
4) That AP can also save you quite a bit of money in other discounts. You can also purchase a Disney Dining Experience card for $50 if you are an AP holder. The DDE card will get you 20% off all meals at a large number of restaurants at WDW.