Your skepticism is extremely common. It usually only takes a little pain induced desperation for a skeptic to come hobbling into the office, and often they will become a regular patient.
As far as children are concerned, I can't really speak on it with much authority. One of our professors is a specialist in pediatric Chiropractic, so I know they exist and work on the same general principles as an average DC.
When it comes to Subluxation/fixation, as I said, most of the biological/scientific mechanisms are generally accepted, which is why insurance companies now cover a great deal of Chiropractic treatments. The real reason Chiropractic was approached with such hesitance is that there was no truly accurate way to measure someone's pain level before and after treatment, because pain is subjective to each individual. This means, unless Chiropractors could prove beyond a doubt that the alleviation of pain is physiological.... the possibility exists that it is mental! So we had to prove ourselves!! Now that the physiological mechanisms are being proven, and we now have more accurate ways to measure pain and improvement, there really is no reason you should hesitate if you or someone you know is in pain.
Even if you are still hesitant, and we were to place all the scientific evidence aside... consider this: for most of the neuromuscular pain Chiropractors have shown success treating, traditional medicine has two options:
1) pain medication, which simply covers up pain and more importantly the condition causing the pain
2) surgery....yikes!
The bottom line is if you have: Low back pain (general or associated with pregnancy), cervicogenic headaches, whiplash, Locked low back, herniated disc, stiff neck, hip pain, shoulder pain, knee pain, etc....... then a reputable Chiro. should be at the top of your list!