Just my two cents:
If the 3 year old whines, please make sure you bring a stroller!!! I took one (double at first, then single comfy one) till my youngest was 7. Even after that, we ended up renting one for a day. It is a lot of walking!
I would feel very comfortable walking from that hotel to Downtown Disney or to Crossroads - there are sidewalks with crosswalks, and so many people do it. Crossroads has some cheap eats places (like McDonald's - we've driven through that one several times in a pinch, yuck to me but what the heck).
I also agree - do not do grocery shopping at Gooding's (at the Crossroads shopping center). If you are flying, how are you getting from the airport? You can book a towncar with a quick grocery stop. When I've done that I usually stop at Target for groceries (once we did Gooding's - yuck they carry almost nothing and it's way overpriced). Or save the trouble and do Garden Grocer - good advice from the previous poster.
For more privacy, if you like the Downtown Disney hotels, the Doubletree is all suites. Just a thought - one could have the sofa sleeper.
I do think without a car and off site, any of the DTD hotels are good for frequent bus transportation.