We don't have kids and we have stayed both offsite and at ASMu.
I offer you my insights. I know that you are going to hear alot about onsite vs. offsite. Some folks are just addicted to staying onsite. I can fairly say, they each have their strengths and weaknesses.
The offsite perspective...
March 2001, regular season, Quality Inn arcross from FAO Schwartz, $30/nite. I hated using my bank check card everywhere. I was worried the whole time about losing it or just spreading the number around so often. But, the purchases went through without a hitch, until the 3rd day when I was forced to call my bank and explain that I was at WDW and it was ok and I was the one charging up a storm. lol I came prepared with cash for the cart vendors and only had to use the ATM once. The other downside was that we had to carry around all the goodies that we bought. We are avid disney collectors, so this became a bit of an issue. We were forced to rent a locker and actually ship some packages home and/or to the front of the park for pick-up on our way out. The line at the package pick-up was an hour long about 45 minutes before the park offically closed. So, at the end of the day, we were more tired and a bit more cranky than I would
have been if I had stayed onsite. The shuttle busses from our hotel did not run as often as I would have liked, so we drove to the parks. The food was cheaper to an extent because we ate offsite more often, but the drive in the traffic was not much fun at the end of the day either. We had to pay for parking. Our family and friends that we met up with on the first night also had to pay to park and it was a bit of a coordination nightmare. We couldn't do EE or an e-night because we were offsite. I was a bit bummed, but you do what you can. We had lucked out on the room cost and they gave us the use of a fridge for free, but it was still offsite. Now, I will say that this was my first trip as an adult and I didn't know how great it was to actually be onsite. I would have told you that it was ok before I actually stayed onsite and had the chance to enjoy the perks.
Onsite perspective.....
September 2002, value season, ASMu, king room with fridge(not charged for it), $49/nite(GA resident rate). We set up my bank check card on the room key. The check card and all other cards lived in the safe during our stay. I carried a bit of cash each day for cart vendors. All purchases went to the hotel gift shop for pick-up at the end of the next day....except of course for the last day's purchases, but we were able to plan so that we didn't buy much that last day. Busses took us to most of the places we wanted to go. We drove only a couple of times, but it was so nice to not have to pay to park. We had additional family coming for the last day of our stay to do MK and the CM at ASMu gave us 2 additional parking passes to allow them to park for free.....Jose was such a nice guy. Pizza delivery to the room was awesome! There were no e-nights and no EE when we were there, but the low crowds made it unnecessary in my opinion. Overall, this trip hooked me into wanting to always stay onsite. I don't know if we will be able to aways do it, but it's what I budget for now.
Finally, yes, it's often times cheaper to stay offsite in respect to the hotel and food. But there are definate perks that make staying in a value resort onsite a better deal for us. Room key charging, package delivery to the resort, free parking, room service, EE & e-nights all make for a very appealing package. In the end, your wallet makes the decision. Mickey