OP: Some of the suggestions ("take a bus to BC, walk to Epcot" or "take a bus to a monorail resort, take monorail to MK") sound more complicated than they are. Provided your kids are willing to ask someone for directions, once they step off the bus (at BC, or BW, or the CR, or wherever) all they have to do is ask another guest how to get to the park in question, or how to get to the boat/monorail. Someone getting off that bus will be able to direct them. Or they can walk to the hotel lobby and ask one of the CMs standing outside of the hotel, or go into the lobby and ask a CM for directions.
In some cases (bus to BW or BC to walk/boat to Epcot or DHS) they would need to walk through the lobby anyway. The bus arrives on the "land" side of the hotel, the walkway/boats are on the lake side, so from the bus stop they would head to the hotel lobby, cross through to the opposite side and head outside again. While they are in the lobby, they can ask for directions.
The other thing that makes this sound complicated is that at the moment, all park options are being considered. (If heading to the MK do this, if Epcot do that, if AK....) Provided they decide on a park BEFORE you head to DS for dinner, you could check with your hotel's concierge for the best route from DS to that park and write it down for them so they have written directions with them when they leave DS. If they don't decide until you are at DS (or change their minds) go to Guest Relations at DS and ask one of the CMs there for written directions.