Hi--I just got back from them yesterday.
No, all of them are are not. A few are.

The Grand and Isle of Capri are next to each other and the Palace directly across the street. However, the Palace and Imperial Palace and Boomtown are quite a hike down a road to get to them away from the main drag. The ones on the east end of the main road (90) are pretty close. I'd say a total of 3-4are fine to walk to. They would be:

Casino Magic
Isle of Capri
The Grand

Others are quite a ways down and unless you have an awful lot of energy i wouldnt even think of walking to them.

If you really want to see them all...you'll need a car or a cab.