If you do two trips a year it's definitely worthwhile considering a AP.
The cost is cheaper for one AP than for two 7-day hoppers. It gets you discounts at The World of Disney store and restaurants. You can get AP rates for rooms. No, accommodations aren't included, but the discounts can pay for a good chuck of the AP cost, but don't depend on discounts being available when you want to go.
There are other benefits, AP-only pins or merchandise, discounts on admissions to some places...
Basically, check if it's cheaper than your tickets during a year would be and if it's close, chances are it'll be worth your while to get APs.