Welcome to the Dis. I live in Fayetteville just south of Atlanta.
Like the other posters have said, the big savings is in the multiple trips. We bought the AP's in December of 2001 with the intention of going to WDW twice (our regular Christmas week and Spring break trips) and low and behold the first year we had them we went to WDW a total of 5 times!
When we went Christmas week 2001, actually 9 days, we went to various parks a total of 8 different days. So they paid for themselves on that trip. We then went in April for Spring break for 6 days, a short trip in May, a 5 day trip in July, and a 4 day trip in October. We then re-newed them for our Christmas week trip in December, went again in April for Spring break and are planning another trip in November. Afterall, the trip is just 6-1/2 hours by car and the biggest expense, tickets, is covered.
Of all of those trips, we only used the AP discount on our last trip for the first week in April. We just made it in under the wire before the AP discounts ran out. All of the other trips we either used post card disount codes, codes from mousesavers.com or the teacher rate at the Dolphin (one trip) and stayed off site one trip (October with discount from mousesavers for Carribe Royal).
I would recommend buying the AP's for multiple trips becasuse there are other discounts available that might be as good or better than AP discounts or their may not be any AP discount available when you want to go. If you are interested in the discounts, I would start with one AP (one adult AP is all you need for the discounts).
You can save money with AP discounts at other Disney resorts. We are using the AP rate to go to Vero Beach in July. This is saving us about $60.00/night over the rack rate. Also, we have a Disney Visa and there is a 20% discount at VB available. However, the AP rate would be less I think. I will call CRO this week end and compare the Disney Vsia code. The great thing about Disney is they will let you change codes to get the lowest rate offered for your stay.
As far as discounts at
Disneyland and cruises, I don't know about those yet. I think there is a discount for AP's at both but not sure. Someone else will read this and answer that for you. Sorry I can't be of more help on that area.
Again, welcome to the Dis!