I have stayed at CBR as a single gentleman (well sometimes I am a gentleman), and did walk to EPCOT, the Studios, and the Boardwalk. I hate waiting.
Leaving the Boardwalk headed south, you go past the parking lot, to the light that controls entry to the Studios. There you can turn left and there is a sidewalk along the north side of the 6 lane road. Walk along this until you reach the next traffic light, which now allows drivers to head south to the Sports Comples and Pop Century. At this point cross to the south side of the road, and you're on the NW corner of the CBR complex. There is not a sidewalk on this side, but you can veer off to the CBR sidewalks and complex. As a rough guess it's 3/4 mile from the Boardwalk Lobby to the CBR corner.
If you're headed to the Studios, Boardwalk, or EPCOT from CBR, just reverse the process. Head NW out of CBR to the corner of the busy streets, Cross to the North side and use the sidewalk, heading West. At the next light, if you're headed for the Studios, cross back and head in (or better, go into the Boardwalk area, hit the path to the Studios and follow that, a bit longer, but much nicer and sefer). If you're headed to the BW or EPCOT, walk up to the hotel, through the passage to the BW, then wherever you like.
Having said I did it, I was alone, without any children to (1) complain about the walk and (2) worry about the traffic, etc. Even though it was possible, I can't say I enjoyed it. With small humans, it probably would have been the pits. In that situation, the busses probably are the way to go.
I really like hanging around the Boardwalk area, so this trek firmly convinced me that when I go to WDW I stay in the Boardwalk area.