It really depends on your home power situation and your gear. I traded down a few years ago from a higher end system, to a nice home theater system and got rid of my RGPC conditioners. I just used a basic Belkin Home theater surge suppresor for the reciever, TV, cable and disc player in that system, and I was very happy. For the money, that was really a great system.
As I moved back into better audio gear, for a couple of months I focused on just the audio gear and didn't do anything about the power. I was pretty happy, then after some research I bought an APC S15 and it was a revelation. Man, it opened up everything sonically. I didn't really see any improvement in the picture quality, but the sound really improved. Deeper, higher, more transparent and faster.
Then I started switching amps, I had been using digital amps (Bel Canto, Spectron, Innersound) and switched over to traditional SS amps (Cary 500MB) and the APC started running out of juice!! Sound would start to degrade at higher volumes. So I bought an PS Audio Duet, and got the amps off of the APC, and "Voila" great sound again. Actually better than ever, and the amps once again opened up, and sounded much better than when just plugged into the wall.
So that's my $0.02. It depends on your gear, and your home's power. Our power sucks, and we get 4 - 5 power surges, noticable, mid day every day. We have fried 3 different control boards on Thermador ovens (thank God for the Home warranty), and more than one laptop has died a painful death. But the audio/video gear is safe.