The only time you get a discount on the annual pass is upon renewal. So if you think you will be getting annual passes as you go forward it is worth it.
If you are in the military you can get a discount on annual passes at Shades of Green, which is the military hotel on the Disney property. You have to show them a military ID when purchasing. Their rates are about $15 - $20 off regular price.
After checking, it looks like you get a discount off the Florida discount through AAA. No discount for AAA members if you are not a Florida resident. Sorry for the misinformation.