APs: We had APs for 1 year. Your best bet is to just figure up how many trips you will take and for how many days. We were doing an annual trip in September so didn't have APs bc our trips didn't fall within 365days of each other. Once we knew we were going back in November, we knew we would be taking 3 trips between Sept.2011, Nov.2011 and Sept.2012. 8 day park hoppers are $355. 3 trips would be $1065)so obviously getting the AP was a much better deal. Even if you are taking 2 trips within 365 days that add up more than the cost of the AP it may be worth it. Where is may not be worth it is if you use the Free Dining promotion and the cost of your trips is close to the cost of the APs. The Free Dining promotion means you pay rack rate for the room but you can save more depending on the make up of your part and how many per room, etc. With the AP, in order to take advantage of the FD promo you have to buy 2 day base tickets for everyone in your party. It is really just a numbers game. Also keep in mind that you can stay off property and still get free parking with the AP, get 10% all merchandise purchases and are eligible for the TIW card. We didn't renew our passes in Sept. bc we weren't planning on anymore trips but that didn't happen and we already went in November and now are planning another April trip so we probably should have. Luckily we have a couple different sets of old tickets around here that we will use for April and still have our TIW card that expires in May. Hope that helps.ETA...I just realized you said you have 18-20 days planned. Let's say you go the cheapest route and use all of those in two trips (more days at Disney = more cost effective). Example with 1 adult ticket for a family that wants to start having an "Annual Trip":Trip 1 on April 1-9th, 2013: 9 days, park hopper $365Trip 2 on March 20-20, 2014: 10 days, park hopper $375 (this price will be higher though bc ticket prices typically increase in June so you get even more savings)Total cost: $740AP cost: $574Shorter more frequent trips are going to save you even more.