Quick recommendation: My readers who are tempted to fall for the monorail siren song, as well as those who have been misled by neanderthal clap-trap about “choo-choo” trains being too old a technology should check out this excellent piece by Christof in Houston.
As I’ve commented in his forums, though, also be aware that these solutions are often pushed disingenuously by people who really want nothing to get done, because they don’t want the status quo to be threatened. In other words, whenever you read about monorail and especially PRT, be aware that a lot of the guys pushing this are doing so not because they actually want or expect it to ever get built, but precisely because they know it WON’T ever get built so they can protect transit funds which can later be diverted for suburban highways instead.