When I had the music store, we sold tons of Planet Waves Classic cables.
They are around $20 and very flexible, and have a lifetime warranty. I really like them.
They have a flange on the ground part of the cable that really makes a great connection to the guitar and amp.
A lot of our customers would ask if the cables had a built in treble circuit.
I think that the higher end cables do make a huge difference if you are using long runs, lots of effects, or have older equipment. Where you will most likely hear the difference is in the type of tones you are using. If you use a lot of distortion, you may not notice an increase in headroom.
A good friend of mine uses the Mogami cord for recording and he said the difference is night and day in his tone. He compared it to a fresh set of batteries in a flashlight.
I design and install Home Theaters, and I know for a fact that there is less noise and much better sound associated with higher end or better made wire.
Monster Cable is mostly hype and advertising, but there are many companies out there that are making some really good wire for much cheaper.
I have to agree that middle of the road is the best bang for the buck.