Last year we stayed off site at Sunset Lakes.
This year we are staying on-site. We had a great time at Sunset Lakes!!!
The kids LOVE LOVE LOVED the house, and having all the extra space was just so nice. Last year we went with grammy and gramps so having the extra room was a must. The kids also loved having their own room, and being able to swim in their 'own pool. The cost for renting the house was definitely less than what we would have spent onsite for the room.
HOWEVER...one thing you have to factor into your trip planning tho - is the cost of van rental. We were away for 10 days, and the Van deal through hotwire (which was a steal in comparison to going directly to the rental sites) was like 300 bucks through Budget Rentacar! IN addition you have to count up the parking fees. Everytime you park its like 10 bucks.
But if you add that plus the cost to heat the pool - the cost came to about what My family paid (wo grammy and gramps there) onsite.
Another thing I didnt like was having to do 'housework' I go on vacation to get away from dishes etc., And also taking out trash etc., I did like tho being able to cook up some quick food for the kids without having to drop
100$ - so each time you have to weigh the pros and cons.
This year we are going back to onsite, because we enjoyed not having to have to drive and having all that transportation at your beck and call. You really cant put a price on how efficiently Disney wisks all these people around.
I know Im posting this opinion in the wrong forum!!

But that is my take on it currently. I understand completely because Im always having this internal debate!