It actually depends. I have priced it out both ways many times. Sometimes the price difference is $300, but sometimes it is only $80. When you get ready to book, you need to price out the package, and then price it out seperately.
The perks are a little different at each place. AAA offers free parking, so if you are staying off sight, and need to drive, this is a value of $10 per day I think. Costco throws in a character breakfast for 4 and a $20 gift card. So that's about $110 worth or so, if you plan on doing a character breakfast anyhow.
All of them give you preferred seating, Toon Town entry, a lanyard, a pin, maybe a coin.
Sometimes a character call to the kids.
For me, if the price difference is $80, then it is worth it, provided I am very sure about my trip.
Otherwise, I much prefer the flexibility of paying seperately and when I want to for tickets, as well as being able to cancel the hotel at a late date without penalty. (sometimes I like to change)