Being DVC, our preference is BWV or BLT both of which we own in, but we have stayed in all of the accomodation sin WDW for DVC. If you ask my hsuband and I, we would prefer OKW over SSR as its more relaxed, bigger rooms - full size washer and dryer in a laundry room (no clost like every otehr one or two bedroom), tropical decor and it is undergoing renovation right now. If you ask our kids (and told them they couildnt stay at BWV or BLT - They are currently 19 and twins are 11) they would opt for SSR as its clsoe to DTD and they could walk there to enjoy the activites there.
Your children are younger and you might really appreciate the extra room at OKW, and they wouldnt have the other resort to compare it too like mine do.
As for buses, we never had an issue at either,
Wtih regard to food, SSR does have the upper hand since you can walk to DTD and eat at the restaurants there, but on the other hand, you can take the boat from OKW to DTD and enjoy the restaurants, just takes a bit more time.
Bottom line for your family OKW in my opinion would be the best bet IF you dont opt for BWV or BC whichare reight at the back door of Epcot and then its location, location, location!