So far the family and I have purchased *only* AP tickets. On our first AP we did two trips totaling about 17 days, and the second AP was good for five trips totaling over 30 days. Yeah, we went kinda crazy on the second one ;-) .
There are many reasons why APs make sense :
1. Compared to regular admission, AP's have a break-even point of about 8 days for the regular, and about 10 days for the premium.
2. Subject to availability, AP's can often provide significant discounts on Disney accommodations. Discounts of 30% to 40% are not unheard of.
3. Once you have reached the break-even point, and subsequent trips that you are able to take are just "icing on the cake." It really does make it easier to plan that second (or third, or fourth ) trip knowing that you will not have to buy admission again !
4. You don't feel like you have "wasted" a day of admission if you only spend a short time in the park. Would you use one of your park-hopper "days" just to ride ONE ride, or to just go to Epcot to eat ? We have done just that with our AP's. Not feeling like you have to do and see as much as possible each day to get your moneys worth from that days ticket cost allows you to slow down, relax, and enjoy Disney in a different way.
One "Con" though - APs make going back addictive ! Stress at work, cold weather at home, and some still-active AP's in the dresser drawer can make the latest discounts at Mary's site really tempting !! If you don't think so, look at the first two trips in my countdown clocks - Yep, water park APs

!!!