Even with the dining package, you will be standing in line for about an hour before getting into the amphitheater. Standby can be very, very long depending on the narrator.
I saw people in the queue for the next CP show back in November, and that show was a couple of hours away!
What we did was to listen to some of the music from outside the amphitheater seating area in the American pavilion. In some areas, you can see the stage from a distance.
IMHO, I personally don't see the attraction, but I know that people love it. CP does seem to bump up attendance in Epcot - my wife overheard several people on our last trip say the only reason they came to Epcot was to see CP.
Those two will have huge lines (both stand-by & dining package) for all performances.Even with the dining package, I've had to stand in line for an hour and I was well back in that line. The two CPs I've gone to were Whoopi and NPH and they are very popular so that may have had something to do with the dining package line being started so far in advance.