I agree with everyone else. When we stayed at CBR, I really wanted to book a preferred room but none were available. Best $150 I ever saved! We were put in Barbados 14 which is one of the more outlying sections for standard rooms (pirate rooms are a teeny bit further I think) and it was perfect. Our walk was around 5-7 minutes at a VERY leisurely pace to OPR, we had two quiet pools very nearby, bus stop very nearby and we enjoyed being close to the Custom House for our Magical Express pick up.
I walked all over that resort, I timed the walks from the various sections and was surprised at how convenient it was.
From my experience if I had extrememly young kids who were in strollers but maybe I didn't have one (as in I was renting my strollers at the parks) I would get preferred or young kids too old for a stroller and also if it was the heat of summer and I didn't want to walk too much in the heat to the pool, I would book preferred. Otherwise I would not.
If you do book preferred, you will be fine. A preferred room at CBR is about as convenient as you get at a Disney resort.
Longest walks I ever had at WDW were at Boardwalk. Down a long hallway (albeit it was air conditioned) to the elevator, than through the lobby, and then walk a bit to the bus stop. I was missing our Barbados location that trip let me tell you.