If you don't mind spending in the $300+ range for a hotel room, check out the Courtyard Anaheim Theme Park Entrance. It's within walking distance to the parks, has awesome waterslides if you're going when it's warm, and has extremely comfortable beds. Our family stayed there when they first opened and it's easily our favorite hotel in the area. The rooms are plenty big for 6 and the staff there are awesome.
The Courtyard Theme Park Entrance is nice, but the water slides are not "awesome" if you are over 12. A 13 year old would look up from their smartphone just long enough to say "lame".
Park Vue Inn. It is the closest off-property hotel (literally right as you cross the street). Since you have a DS who is 4 it is convenient to come back to the hotel for a rest in the afternoon.
Technically the Best Western Plus Park Place Inn is closer.
We're a family of six and enjoy staying within walking distance and having a free breakfast with hot/protein foods included (eggs, sausage, etc). We have a 4 year old son and an 8 year old daughter too! Our older two are teenagers though. Anyway, I second the Park Vue. We have a 2 Queen + bunk bed room booked for New Year's. I believe they only have two of those types of rooms in the whole hotel, so book early. For more of our experiences with walking-distance hotels, you can read my post here:
Where are you staying on your next Disneyland Trip and Why?.
That list of hotels in the hyperlink is a walk through Yesterland of 50 year old hotels.
The SpringHill Suites Anaheim Resort Convention Center, Homewood Suites Anaheim Resort Convention Center, Hyatt House Anaheim Resort Convention Center and Residence Inn Anaheim Resort Convention Center (not Maingate) are all new, two are less than a month old, they have Family Suites and have great pool areas.
If you are referring to Embassy Suites S it is further down from Hilton, definitely not walkable to the park. ART doesn't go that far but they do have their own shuttle (for a fee) shared with 2 other hotels that are right there. Let's just say it was about the only thing we liked about the hotel.
Bad information all the way around. Walkable is a matter of personal fitness. The Embassy Suites South is only 1.5 miles from the entrance plaza. I call that walkable.
The ART definitely goes that far, both Route 1 & Route 2 go there.
For Hilton properties besides the Anaheim Hilton, Homewood Suites Anaheim Resort Convention Center, Embassy Suites South you have the Hilton Garden Inn, Hampton Inn, DoubleTree and a second Homewood Suites.
There is also a third Residence Inn right by the Embassy Suites South.